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/features/vehicles/domain/vehicles.service.ts

@@ -19,6 +19,7 @@ import * as path from 'path';
 import { isValidVIN, isValidPreModernVIN } from '../../../shared-minimal/utils/validators';
 import { normalizeMakeName, normalizeModelName } from './name-normalizer';
 import { getVehicleDataService, getPool } from '../../platform';
+import { auditLogService } from '../../audit-log';
 
 export class VehiclesService {
   private readonly cachePrefix = 'vehicles';
@@ -61,9 +62,20 @@ export class VehiclesService {
     // Invalidate user's vehicle list cache
     await this.invalidateUserCache(userId);
 
+    // Log vehicle creation to unified audit log
+    const vehicleDesc = [vehicle.year, vehicle.make, vehicle.model].filter(Boolean).join(' ');
+    await auditLogService.info(
+      'vehicle',
+      userId,
+      `Vehicle created: ${vehicleDesc || vehicle.id}`,
+      'vehicle',
+      vehicle.id,
+      { vin: vehicle.vin, make: vehicle.make, model: vehicle.model, year: vehicle.year }
+    ).catch(err => logger.error('Failed to log vehicle create audit event', { error: err }));
+
     return this.toResponse(vehicle);
   }
-  
+
   async getUserVehicles(userId: string): Promise<VehicleResponse[]> {
     const cacheKey = `${this.cachePrefix}:user:${userId}`;
     
@@ -154,9 +166,20 @@ export class VehiclesService {
     // Invalidate cache
     await this.invalidateUserCache(userId);
 
+    // Log vehicle update to unified audit log
+    const vehicleDesc = [updated.year, updated.make, updated.model].filter(Boolean).join(' ');
+    await auditLogService.info(
+      'vehicle',
+      userId,
+      `Vehicle updated: ${vehicleDesc || id}`,
+      'vehicle',
+      id,
+      { updatedFields: Object.keys(data) }
+    ).catch(err => logger.error('Failed to log vehicle update audit event', { error: err }));
+
     return this.toResponse(updated);
   }
-  
+
   async deleteVehicle(id: string, userId: string): Promise<void> {
     // Verify ownership
     const existing = await this.repository.findById(id);
@@ -225,6 +248,17 @@ export class VehiclesService {
 
     // Invalidate cache
     await this.invalidateUserCache(userId);
+
+    // Log vehicle deletion to unified audit log
+    const vehicleDesc = [existing.year, existing.make, existing.model].filter(Boolean).join(' ');
+    await auditLogService.info(
+      'vehicle',
+      userId,
+      `Vehicle deleted: ${vehicleDesc || id}`,
+      'vehicle',
+      id,
+      { vin: existing.vin, make: existing.make, model: existing.model, year: existing.year }
+    ).catch(err => logger.error('Failed to log vehicle delete audit event', { error: err }));
   }
 
   async getVehicleRaw(id: string, userId: string): Promise<Vehicle | null> {