feat(08-03): FavoriteLink schema + FavoritesModule (CRUD + SSRF icon discovery)

- Add FavoriteLink Prisma model (userId/tenantId/widgetId scope, iconUrl nullable, position)
- IconDiscoveryService: port SSRF-protected icon discovery with redirect: 'manual',
  private IP / blocked-hostname checks, 4000ms timeout, 200k HTML cap (T-08-05)
- FavoritesService: list/create/update/remove all scoped by userId (T-08-06 / Pitfall 3)
- FavoritesController: GET /favorites?widgetId, POST, PATCH :id, DELETE :id
- FavoritesModule registered in AppModule
- tsc --noEmit passes for @tessera/api

apps/api/src/app.module.ts

@@ -12,6 +12,7 @@ import { MailModule } from './mail/mail.module';
 import { CalendarModule } from './calendar/calendar.module';
 import { DashboardModule } from './dashboard/dashboard.module';
 import { DkvModule } from './dkv/dkv.module';
+import { FavoritesModule } from './favorites/favorites.module';
 import { DomaincheckModule } from './domaincheck/domaincheck.module';
 import { ModuleRegistryModule } from './module-registry/module-registry.module';
 import { PrismaModule } from './prisma/prisma.module';
@@ -37,6 +38,7 @@ import { UserModule } from './user/user.module';
     CalendarModule,
     SettingsModule,
     DkvModule,
+    FavoritesModule,
   ],
   providers: [
     // Global JWT guard: all routes require auth unless @Public()