feat(billing): manual cadence + fix admin date inputs ignoring date-format setting

Manual billing cadence
  Adds a "Manual (trigger only)" cadence alongside monthly/quarterly. It reuses
  the monthly draft accumulator — invoices and billed hours pile onto one running
  draft — but stores NULL monthly_period_start/end so the scheduler's auto-flush
  never matches. The draft ships only when an admin clicks "Trigger invoice now".
  No migration: billing_cadence is a free-form string column gated by validators.
  - adminCustomers.js: allow 'manual' in billing_cadence validator
  - invoiceService.js: route manual through accumulator; NULL periods + placeholder
    issue/due date in getOrCreateMonthlyDraft
  - customerHoursService.js: manual auto-appends hours to running draft;
    billUnbilledEntries refuses manual (CADENCE_MISMATCH)
  - CustomerDetailPage.tsx: dropdown option, cycle-day hidden for manual,
    NULL-period-safe draft preview + trigger button, manual-specific copy
  - customerAdmin.service.ts: cadence union + nullable periodStart/periodEnd
  - en.json / de.json: manual, triggerConfirmManual, triggerHintManual,
    draftPreview.titleManual
Date-format fixes
  Replace raw <input type="date"> (browser-locale) with LocalizedDateInput so
  these admin surfaces honor the general_date_format setting:
  - ContractEditorPage.tsx (issue / valid-until / event dates)
  - QuoteEditorPage.tsx (event / valid-until dates)
  - EventDetailsPage.tsx (expiry date)
  - HoursSection.tsx (entry date)

frontend/src/pages/admin/CustomerDetailPage.tsx

@@ -77,7 +77,7 @@ export const CustomerDetailPage: React.FC = () => {
     queryKey: ['admin-customer-monthly-draft', customerId],
     queryFn: () => customerAdminService.getMonthlyDraft(customerId),
     enabled: Number.isFinite(customerId) && customerId > 0
-      && (customer?.billingCadence === 'monthly'),
+      && (customer?.billingCadence === 'monthly' || customer?.billingCadence === 'manual'),
   });
   const monthlyDraft = monthlyDraftRes?.draft || null;
 
@@ -716,9 +716,10 @@ export const CustomerDetailPage: React.FC = () => {
               <option value="per_event">{t('customers.billing.perEvent', 'Per event')}</option>
               <option value="monthly">{t('customers.billing.monthly', 'Monthly')}</option>
               <option value="quarterly">{t('customers.billing.quarterly', 'Quarterly')}</option>
+              <option value="manual">{t('customers.billing.manual', 'Manual (trigger only)')}</option>
             </select>
           </div>
-          {form.billingCadence && form.billingCadence !== 'per_event' && (
+          {(form.billingCadence === 'monthly' || form.billingCadence === 'quarterly') && (
             <div>
               <label className="block text-sm font-medium text-theme mb-1">
                 {t('customers.billing.cycleDay', 'Cycle day')}
@@ -763,21 +764,26 @@ export const CustomerDetailPage: React.FC = () => {
             period so admin sees exactly what "Trigger invoice now"
             would ship. Hidden when no draft exists yet (admin hasn't
             saved anything onto the period). */}
-        {form.billingCadence === 'monthly' && monthlyDraft && monthlyDraft.lineItems.length > 0 && (
+        {(form.billingCadence === 'monthly' || form.billingCadence === 'manual') && monthlyDraft && monthlyDraft.lineItems.length > 0 && (
           <div className="mt-4 pt-4 border-t border-neutral-200 dark:border-neutral-700">
             <div className="flex items-center justify-between mb-2">
               <h3 className="text-sm font-semibold text-theme">
-                {t('customers.billing.draftPreview.title',
-                  'Pending in this month\'s bill')}
+                {form.billingCadence === 'manual'
+                  ? t('customers.billing.draftPreview.titleManual',
+                      'Pending — ships on manual trigger')
+                  : t('customers.billing.draftPreview.title',
+                      'Pending in this month\'s bill')}
               </h3>
               <span className="text-xs text-muted-theme">
-                {t('customers.billing.draftPreview.periodRange',
-                  '{{number}} · {{from}} – {{to}}',
-                  {
-                    number: monthlyDraft.invoiceNumber,
-                    from: fmtDate(monthlyDraft.periodStart),
-                    to: fmtDate(monthlyDraft.periodEnd),
-                  })}
+                {monthlyDraft.periodStart && monthlyDraft.periodEnd
+                  ? t('customers.billing.draftPreview.periodRange',
+                      '{{number}} · {{from}} – {{to}}',
+                      {
+                        number: monthlyDraft.invoiceNumber,
+                        from: fmtDate(monthlyDraft.periodStart),
+                        to: fmtDate(monthlyDraft.periodEnd),
+                      })
+                  : monthlyDraft.invoiceNumber}
               </span>
             </div>
             <div className="rounded-lg border border-neutral-200 dark:border-neutral-700 overflow-hidden">
@@ -834,20 +840,25 @@ export const CustomerDetailPage: React.FC = () => {
           </div>
         )}
 
-        {/* Manual trigger — issue the running monthly draft NOW
-            instead of waiting for the cadence-day scheduler tick.
-            Only shown for monthly-mode customers (per-event has no
-            draft to arm; the equivalent action there is "Bill these
-            hours" on the standalone Hours-logging page). */}
-        {form.billingCadence === 'monthly' && (
+        {/* Manual trigger — issue the running draft NOW. For monthly
+            customers this bypasses the cadence-day scheduler tick; for
+            manual-cadence customers it's the ONLY way the draft ships
+            (the scheduler never auto-flushes a manual draft). Per-event
+            has no draft to arm; the equivalent action there is "Bill
+            these hours" on the standalone Hours-logging page. */}
+        {(form.billingCadence === 'monthly' || form.billingCadence === 'manual') && (
           <div className="mt-4 pt-4 border-t border-neutral-200 dark:border-neutral-700">
             <Button
               variant="outline"
               disabled={triggerMonthlyBillMutation.isPending}
               isLoading={triggerMonthlyBillMutation.isPending}
               onClick={() => {
-                if (window.confirm(t('customers.billing.triggerConfirm',
-                  'Issue this customer\'s monthly bill now? The customer receives the email immediately.') as string)) {
+                const confirmMsg = form.billingCadence === 'manual'
+                  ? t('customers.billing.triggerConfirmManual',
+                      'Issue this customer\'s accumulated bill now? The customer receives the email immediately.')
+                  : t('customers.billing.triggerConfirm',
+                      'Issue this customer\'s monthly bill now? The customer receives the email immediately.');
+                if (window.confirm(confirmMsg as string)) {
                   triggerMonthlyBillMutation.mutate();
                 }
               }}
@@ -855,8 +866,11 @@ export const CustomerDetailPage: React.FC = () => {
               {t('customers.billing.triggerNow', 'Trigger invoice now')}
             </Button>
             <p className="text-xs text-muted-theme mt-2">
-              {t('customers.billing.triggerHint',
-                'Bypasses the cadence day and issues the running draft immediately. Refuses when nothing has been queued for the current period.')}
+              {form.billingCadence === 'manual'
+                ? t('customers.billing.triggerHintManual',
+                    'Issues the running draft immediately. Manual-cadence drafts never ship automatically — this is the only way to send them. Refuses when nothing has been queued.')
+                : t('customers.billing.triggerHint',
+                    'Bypasses the cadence day and issues the running draft immediately. Refuses when nothing has been queued for the current period.')}
             </p>
           </div>
         )}

frontend/src/pages/admin/EventDetailsPage.tsx

@@ -57,7 +57,7 @@ const safeParseDate = (dateValue: unknown): Date | null => {
 import { toast } from 'react-toastify';
 import { useLocalizedDate } from '../../hooks/useLocalizedDate';
 
-import { Button, Input, Card, Loading, MarkdownContent } from '../../components/common';
+import { Button, Input, Card, Loading, MarkdownContent, LocalizedDateInput } from '../../components/common';
 import { EventCategoryManager, AdminPhotoGrid, AdminPhotoViewer, PhotoFilters, PasswordResetModal, ThemeCustomizerEnhanced, ThemeDisplay, HeroPhotoSelector, FocalPointPicker, PhotoUploadModal, FeedbackSettings, FeedbackModerationPanel, EventRenameDialog, PhotoFilterPanel, PhotoExportMenu, AdminGuestsList } from '../../components/admin';
 import { CustomerAccountPicker } from '../../components/admin/CustomerAccountPicker';
 import { EventReminderOverrideCard } from '../../components/admin/EventReminderOverrideCard';
@@ -1194,10 +1194,9 @@ export const EventDetailsPage: React.FC = () => {
                   <label className="block text-sm font-medium text-neutral-700 dark:text-neutral-300 mb-1">
                     {t('events.expirationDate')}
                   </label>
-                  <Input
-                    type="date"
+                  <LocalizedDateInput
                     value={editForm.expires_at}
-                    onChange={(e) => setEditForm(prev => ({ ...prev, expires_at: e.target.value }))}
+                    onChange={(iso) => setEditForm(prev => ({ ...prev, expires_at: iso }))}
                     min={format(new Date(), 'yyyy-MM-dd')}
                   />
                 </div>

frontend/src/pages/admin/contracts/ContractEditorPage.tsx

@@ -17,7 +17,7 @@ import { useNavigate, useParams, Link } from 'react-router-dom';
 import { useQuery, useMutation } from '@tanstack/react-query';
 import { toast } from 'react-toastify';
 import { ArrowLeft, Eye, Save } from 'lucide-react';
-import { Button, Card, Input, Loading } from '../../../components/common';
+import { Button, Card, Input, Loading, LocalizedDateInput } from '../../../components/common';
 import {
   contractsService,
   type ContractBlockSection,
@@ -380,13 +380,13 @@ export const ContractEditorPage: React.FC = () => {
             <label className="block text-sm font-medium mb-1">
               {t('contracts.editor.issueDate', 'Issue date')}
             </label>
-            <Input type="date" value={issueDate} onChange={(e) => setIssueDate(e.target.value)} />
+            <LocalizedDateInput value={issueDate} onChange={setIssueDate} />
           </div>
           <div>
             <label className="block text-sm font-medium mb-1">
               {t('contracts.editor.validUntil', 'Sign by (optional)')}
             </label>
-            <Input type="date" value={validUntil} onChange={(e) => setValidUntil(e.target.value)} />
+            <LocalizedDateInput value={validUntil} onChange={setValidUntil} />
           </div>
         </div>
 
@@ -419,7 +419,7 @@ export const ContractEditorPage: React.FC = () => {
               <label className="block text-sm font-medium mb-1">
                 {t('contracts.editor.eventDate', 'Event date')}
               </label>
-              <Input type="date" value={eventDate} onChange={(e) => setEventDate(e.target.value)} />
+              <LocalizedDateInput value={eventDate} onChange={setEventDate} />
             </div>
             <div className="grid grid-cols-2 gap-2">
               <div>

frontend/src/pages/admin/quotes/QuoteEditorPage.tsx

@@ -16,7 +16,7 @@ import { useTranslation } from 'react-i18next';
 import { useNavigate, useParams, useSearchParams } from 'react-router-dom';
 import { useQuery, useQueryClient } from '@tanstack/react-query';
 import { ArrowLeft, Eye, Send } from 'lucide-react';
-import { Button, Card, Loading, Input } from '../../../components/common';
+import { Button, Card, Loading, Input, LocalizedDateInput } from '../../../components/common';
 import {
   quotesService,
   type QuoteCreatePayload,
@@ -490,8 +490,8 @@ export const QuoteEditorPage: React.FC = () => {
         <div className="grid grid-cols-1 md:grid-cols-2 gap-3">
           <Input label={t('quotes.field.eventName', 'Event name') as string} value={form.eventName}
             onChange={(e) => setForm((f) => ({ ...f, eventName: e.target.value }))} />
-          <Input type="date" label={t('quotes.field.eventDate', 'Event date') as string} value={form.eventDate}
-            onChange={(e) => setForm((f) => ({ ...f, eventDate: e.target.value }))} />
+          <LocalizedDateInput label={t('quotes.field.eventDate', 'Event date') as string} value={form.eventDate}
+            onChange={(iso) => setForm((f) => ({ ...f, eventDate: iso }))} />
           <Input type="time" lang={timeInputLang} label={t('quotes.field.eventTimeStart', 'Start time') as string} value={form.eventTimeStart}
             onChange={(e) => setForm((f) => ({ ...f, eventTimeStart: e.target.value }))} />
           <Input type="time" lang={timeInputLang} label={t('quotes.field.eventTimeEnd', 'End time') as string} value={form.eventTimeEnd}
@@ -499,8 +499,8 @@ export const QuoteEditorPage: React.FC = () => {
           <Input type="number" step="0.5" label={t('quotes.field.expectedDuration', 'Expected duration (h)') as string}
             value={form.expectedDurationHours}
             onChange={(e) => setForm((f) => ({ ...f, expectedDurationHours: e.target.value }))} />
-          <Input type="date" label={t('quotes.field.validUntil', 'Valid until') as string} value={form.validUntil}
-            onChange={(e) => setForm((f) => ({ ...f, validUntil: e.target.value }))} />
+          <LocalizedDateInput label={t('quotes.field.validUntil', 'Valid until') as string} value={form.validUntil}
+            onChange={(iso) => setForm((f) => ({ ...f, validUntil: iso }))} />
         </div>
       </Card>