feat: move configuration from .env to DB with Admin UI management

Replace hardcoded .env configuration with database-backed settings
manageable through the Admin web interface. This reduces .env to
bootstrap-only variables (DB, Keycloak, encryption keys).

Backend:
- Add SystemSetting Prisma model with category, valueType, isSecret
- Add system-settings NestJS module (CRUD, 60s cache, encryption)
- Refactor all 7 connectors to lazy-load credentials from DB via
  CredentialsService.findActiveByType() instead of ConfigService
- Add event-driven credential reload (@nestjs/event-emitter)
- Dynamic CORS origins and conditional Swagger from DB settings
- Fix JWT strategy: use Keycloak JWKS (RS256) instead of symmetric secret
- Add SYSTEM_SETTINGS_VIEW/MANAGE permissions
- Seed 13 default settings (sync intervals, features, branding, CORS)
- Add env-to-db migration script (prisma/migrate-env-to-db.ts)

Frontend:
- Add use-credentials hook (full CRUD for integration credentials)
- Add use-system-settings hook (read/update system settings)
- Wire admin-integrations page to real API (create/update/test/toggle)
- Add admin system-settings page with 4 tabs (Branding, CORS, Sync, Features)
- Fix sidebar double-highlighting with exactMatch flag
- Fix integration detail fallback when API unavailable
- Fix API client to unwrap backend's {success, data} envelope
- Update NEXT_PUBLIC_API_URL to include /v1 version prefix
- Fix activity-widget hydration error
- Add i18n keys for systemSettings (de + en)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pnpm-lock.yaml

@@ -32,6 +32,9 @@ importers:
       '@nestjs/core':
         specifier: ^10.3.0
         version: 10.4.22(@nestjs/common@10.4.22(class-transformer@0.5.1)(class-validator@0.14.3)(reflect-metadata@0.2.2)(rxjs@7.8.2))(@nestjs/platform-express@10.4.22)(reflect-metadata@0.2.2)(rxjs@7.8.2)
+      '@nestjs/event-emitter':
+        specifier: ^3.0.1
+        version: 3.0.1(@nestjs/common@10.4.22(class-transformer@0.5.1)(class-validator@0.14.3)(reflect-metadata@0.2.2)(rxjs@7.8.2))(@nestjs/core@10.4.22)
       '@nestjs/jwt':
         specifier: ^10.2.0
         version: 10.2.0(@nestjs/common@10.4.22(class-transformer@0.5.1)(class-validator@0.14.3)(reflect-metadata@0.2.2)(rxjs@7.8.2))
@@ -1157,6 +1160,12 @@ packages:
       '@nestjs/websockets':
         optional: true
 
+  '@nestjs/event-emitter@3.0.1':
+    resolution: {integrity: sha512-0Ln/x+7xkU6AJFOcQI9tIhUMXVF7D5itiaQGOyJbXtlAfAIt8gzDdJm+Im7cFzKoWkiW5nCXCPh6GSvdQd/3Dw==}
+    peerDependencies:
+      '@nestjs/common': ^10.0.0 || ^11.0.0
+      '@nestjs/core': ^10.0.0 || ^11.0.0
+
   '@nestjs/jwt@10.2.0':
     resolution: {integrity: sha512-x8cG90SURkEiLOehNaN2aRlotxT0KZESUliOPKKnjWiyJOcWurkF3w345WOX0P4MgFzUjGoZ1Sy0aZnxeihT0g==}
     peerDependencies:
@@ -3526,6 +3535,9 @@ packages:
     resolution: {integrity: sha512-aIL5Fx7mawVa300al2BnEE4iNvo1qETxLrPI/o05L7z6go7fCw1J6EQmbK4FmJ2AS7kgVF/KEZWufBfdClMcPg==}
     engines: {node: '>= 0.6'}
 
+  eventemitter2@6.4.9:
+    resolution: {integrity: sha512-JEPTiaOt9f04oa6NOkc4aH+nVp5I3wEjpHbIPqfgCdD5v5bUzy7xQqwcVO2aDQgOWhI28da57HksMrzK9HlRxg==}
+
   eventemitter3@4.0.7:
     resolution: {integrity: sha512-8guHBZCwKnFhYdHr2ysuRWErTwhoN2X8XELRlrRwpmfeY2jjuUN4taQMsULKUVo1K4DvZl+0pgfyoysHxvmvEw==}
 
@@ -7000,6 +7012,12 @@ snapshots:
     transitivePeerDependencies:
       - encoding
 
+  '@nestjs/event-emitter@3.0.1(@nestjs/common@10.4.22(class-transformer@0.5.1)(class-validator@0.14.3)(reflect-metadata@0.2.2)(rxjs@7.8.2))(@nestjs/core@10.4.22)':
+    dependencies:
+      '@nestjs/common': 10.4.22(class-transformer@0.5.1)(class-validator@0.14.3)(reflect-metadata@0.2.2)(rxjs@7.8.2)
+      '@nestjs/core': 10.4.22(@nestjs/common@10.4.22(class-transformer@0.5.1)(class-validator@0.14.3)(reflect-metadata@0.2.2)(rxjs@7.8.2))(@nestjs/platform-express@10.4.22)(reflect-metadata@0.2.2)(rxjs@7.8.2)
+      eventemitter2: 6.4.9
+
   '@nestjs/jwt@10.2.0(@nestjs/common@10.4.22(class-transformer@0.5.1)(class-validator@0.14.3)(reflect-metadata@0.2.2)(rxjs@7.8.2))':
     dependencies:
       '@nestjs/common': 10.4.22(class-transformer@0.5.1)(class-validator@0.14.3)(reflect-metadata@0.2.2)(rxjs@7.8.2)
@@ -9528,6 +9546,8 @@ snapshots:
 
   etag@1.8.1: {}
 
+  eventemitter2@6.4.9: {}
+
   eventemitter3@4.0.7: {}
 
   events@3.3.0: {}