feat(crm): cross-link to CRM settings from quote + invoice editors

Add a 'Configure defaults in Settings' link (opens Settings → CRM in a
new tab) under the payment-conditions section of the quote and invoice
editors, so the admin can jump to the payment-term / Skonto / numbering
defaults without hunting for the settings page.

frontend/src/i18n/locales/de.json

@@ -76,6 +76,7 @@
   "common": {
     "loading": "Wird geladen...",
     "error": "Fehler",
+    "configureInSettings": "Standards in den Einstellungen anpassen ↗",
     "save": "Speichern",
     "cancel": "Abbrechen",
     "delete": "Löschen",

frontend/src/i18n/locales/en.json

@@ -76,6 +76,7 @@
   "common": {
     "loading": "Loading...",
     "error": "Error",
+    "configureInSettings": "Configure defaults in Settings ↗",
     "save": "Save",
     "cancel": "Cancel",
     "delete": "Delete",

frontend/src/pages/admin/bills/BillEditorPage.tsx

@@ -653,6 +653,10 @@ export const BillEditorPage: React.FC = () => {
           only has the single FK still resolve their preview text. */}
       <Card>
         <h3 className="font-semibold mb-2">{t('bills.section.payment', 'Payment conditions')}</h3>
+        <a href="/admin/settings?tab=crm" target="_blank" rel="noopener noreferrer"
+          className="text-xs text-accent hover:underline mb-2 inline-block">
+          {t('common.configureInSettings', 'Configure defaults in Settings ↗')}
+        </a>
         <div className="grid grid-cols-1 md:grid-cols-2 gap-3">
           <div>
             <label className="block text-sm font-medium mb-1">{t('bills.field.paymentNetDays', 'Net days')}</label>

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

@@ -536,6 +536,10 @@ export const QuoteEditorPage: React.FC = () => {
           below now reads from the timing template. */}
       <Card>
         <h3 className="font-semibold mb-2">4. {t('quotes.section.payment', 'Payment conditions')}</h3>
+        <a href="/admin/settings?tab=crm" target="_blank" rel="noopener noreferrer"
+          className="text-xs text-accent hover:underline mb-2 inline-block">
+          {t('common.configureInSettings', 'Configure defaults in Settings ↗')}
+        </a>
         <div className="grid grid-cols-1 md:grid-cols-2 gap-3">
           <div>
             <label className="block text-sm font-medium mb-1">{t('quotes.field.paymentNetDays', 'Net days')}</label>