feat(projects): gate Project Overview behind a projects feature flag + cockpit email actions

- Migration 120 seeds the projects flag (default OFF), idempotent.
- Backend feature-flags whitelist + DEFAULT_FLAGS + clients derivation.
- adminProjects routes 403 PROJECTS_DISABLED when the flag is off.
- projectService email actions (resend/cancel/retry/send-now) + routes.
- Frontend flag type, DEFAULT_FLAGS, Features tab card (en+de).

frontend/src/contexts/FeatureFlagsContext.tsx

@@ -45,6 +45,10 @@ export const DEFAULT_FLAGS: FeatureFlags = {
   // Settings → Features once they've reviewed the seeded block
   // library with their lawyer.
   contracts: false,
+  // Projects (migration 120). Admin-only grouping layer above events +
+  // the Project Overview cockpit. Off by default — admin opts in under
+  // Settings → Features once they want the CRM → Overview area.
+  projects: false,
 };
 
 export const FEATURE_FLAGS_QUERY_KEY = ['feature-flags'] as const;

frontend/src/features/settings/tabs/FeaturesTab.tsx

@@ -16,6 +16,7 @@ import {
   Briefcase,
   Wrench,
   Calculator,
+  FolderKanban,
 } from 'lucide-react';
 import { useTranslation } from 'react-i18next';
 import { Button, Card } from '../../../components/common';
@@ -291,6 +292,20 @@ export const FeaturesTab: React.FC = () => {
             enabled={staged.hoursLogging}
             onToggle={(next) => setFlag('hoursLogging', next)}
           />
+
+          <FeatureCard
+            icon={FolderKanban}
+            title={t('settings.features.projects.title', 'Projects')}
+            description={t(
+              'settings.features.projects.description',
+              'Admin-only grouping layer above events. Bundle several events under one project and open a 360° Project Overview cockpit — milestone timeline plus a dated feed of every email (with the actual sent preview + resend/cancel/retry actions), quote, contract, invoice, gallery and logged hour. Adds a "book to project" control when logging hours. Customers never see projects.',
+            )}
+            status="new"
+            statusLabel={statusLabel('new')}
+            sidebarLabel={t('settings.features.projects.sidebar', 'Overview')}
+            enabled={staged.projects}
+            onToggle={(next) => setFlag('projects', next)}
+          />
         </Section>
 
         {/* Insights & Access */}

frontend/src/i18n/locales/de.json

@@ -1666,6 +1666,11 @@
         "title": "Stundenerfassung",
         "description": "Zeiterfassung pro Kunde. Admin erfasst Datum + Start-/Endzeit + optionalen Satz-Override + Notiz. Kunden im Monatsmodus akkumulieren Stunden automatisch in den laufenden Monatsentwurf; Kunden pro Anlass sehen eine Schaltfläche „Entwurfsrechnung erstellen“, die eine eigenständige Entwurfsrechnung mit einer Zeile pro Eintrag erzeugt. Unabhängig von Rechnungen — Stunden erfassen, noch bevor die volle Abrechnungsoberfläche aktiviert ist.",
         "sidebar": "Stunden"
+      },
+      "projects": {
+        "title": "Projekte",
+        "description": "Nur-Admin-Gruppierungsebene über Events. Bündle mehrere Events unter einem Projekt und öffne ein 360°-Projektübersichts-Cockpit — Meilenstein-Zeitleiste plus ein datierter Verlauf aller E-Mails (mit der tatsächlich gesendeten Vorschau + Erneut-senden/Abbrechen/Wiederholen-Aktionen), Angebote, Verträge, Rechnungen, Galerien und erfassten Stunden. Fügt beim Erfassen von Stunden eine „Auf Projekt buchen“-Option hinzu. Kunden sehen Projekte nie.",
+        "sidebar": "Übersicht"
       }
     },
     "customerSurface": {

frontend/src/i18n/locales/en.json

@@ -1224,6 +1224,11 @@
         "title": "Hours logging",
         "description": "Per-customer time tracking. Admin logs date + start/end times + optional rate override + note. Monthly-mode customers auto-accumulate hours into the running monthly draft; per-event customers see a \"Create draft invoice\" button that mints a standalone draft invoice with one line per entry. Independent of Bills — log hours even before turning the full billing surface on.",
         "sidebar": "Hours"
+      },
+      "projects": {
+        "title": "Projects",
+        "description": "Admin-only grouping layer above events. Bundle several events under one project and open a 360° Project Overview cockpit — milestone timeline plus a dated feed of every email (with the actual sent preview + resend/cancel/retry actions), quote, contract, invoice, gallery and logged hour. Adds a \"book to project\" control when logging hours. Customers never see projects.",
+        "sidebar": "Overview"
       }
     },
     "customerSurface": {

frontend/src/services/featureFlags.service.ts

@@ -41,7 +41,11 @@ export type FeatureKey =
   // upload. Independent of quotes / bills — contracts can be sent on
   // their own. Seeded block bodies are examples only; admins must
   // have their lawyer review before sending. See docs/crm-disclaimers.md.
-  | 'contracts';
+  | 'contracts'
+  // Projects (migration 120). Admin-only grouping layer above events with the
+  // 360° Project Overview cockpit + the "book to project" hours control. Off
+  // by default; gates the CRM → Overview area entirely.
+  | 'projects';
 
 export type FeatureFlags = Record<FeatureKey, boolean>;