feat(admin): super-admin user detail dashboard

Add a read-only User Detail dashboard for super admins, reachable by
clicking a user name in the admin users list.

Backend: new `admin` module aggregating existing domain services
(no new entities). ADMIN-only endpoints under /api/v1/admin:
overview (profile, account status, wallet balance, revenue, summary
counts), wallet transactions, applications (incl. deleted/docked with
restore eligibility), build/deploy errors, tickets with conversation,
and a composite activity timeline. Adds BillingService.getRevenueSummary
and guards against a wallet get-or-create race in the overview reads.

Frontend: tabbed detail page (overview/applications/activity/errors/
tickets) with lazy per-tab queries; user names in the admin list link to
it (admin only); fa/en i18n keys and response types.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/app.module.ts

@@ -14,6 +14,7 @@ import { BillingModule } from './billing/billing.module';
 import { SnapshotsModule } from './snapshots/snapshots.module';
 import { LifecycleModule } from './lifecycle/lifecycle.module';
 import { ApplicationMigrationsModule } from './application-migrations/application-migrations.module';
+import { AdminModule } from './admin/admin.module';
 import configuration from './config/configuration';
 
 @Module({
@@ -66,6 +67,7 @@ import configuration from './config/configuration';
     SnapshotsModule,
     LifecycleModule,
     ApplicationMigrationsModule,
+    AdminModule,
   ],
 })
 export class AppModule {}