feat: Implement centralized audit logging admin interface (refs #10)

- Add audit_logs table with categories, severities, and indexes
- Create AuditLogService and AuditLogRepository
- Add REST API endpoints for viewing and exporting logs
- Wire audit logging into auth, vehicles, admin, and backup features
- Add desktop AdminLogsPage with filters and CSV export
- Add mobile AdminLogsMobileScreen with card layout
- Implement 90-day retention cleanup job
- Remove old AuditLogPanel from AdminCatalogPage

Security fixes:
- Escape LIKE special characters to prevent pattern injection
- Limit CSV export to 5000 records to prevent memory exhaustion
- Add truncation warning headers for large exports

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/src/app.ts

@@ -25,6 +25,7 @@ import { documentsRoutes } from './features/documents/api/documents.routes';
 import { maintenanceRoutes } from './features/maintenance';
 import { platformRoutes } from './features/platform';
 import { adminRoutes } from './features/admin/api/admin.routes';
+import { auditLogRoutes } from './features/audit-log/api/audit-log.routes';
 import { notificationsRoutes } from './features/notifications';
 import { userProfileRoutes } from './features/user-profile';
 import { onboardingRoutes } from './features/onboarding';
@@ -137,6 +138,7 @@ async function buildApp(): Promise<FastifyInstance> {
   await app.register(communityStationsRoutes, { prefix: '/api' });
   await app.register(maintenanceRoutes, { prefix: '/api' });
   await app.register(adminRoutes, { prefix: '/api' });
+  await app.register(auditLogRoutes, { prefix: '/api' });
   await app.register(notificationsRoutes, { prefix: '/api' });
   await app.register(userProfileRoutes, { prefix: '/api' });
   await app.register(userPreferencesRoutes, { prefix: '/api' });