feat: Phase 3 - AES encryption, SQL audit engine, audit logs (85 tests)

Phase 3.1: Instance password AES-256-GCM encryption
Phase 3.2: SQL audit rule engine (10 rules)
Phase 3.3: Auto-audit on ticket creation
Phase 3.4: Operation audit logs + GET /audit/logs
Tests: 44 -> 85 (41 new), Frontend: AuditLogsPage

frontend/src/hooks/useAuth.tsx

@@ -46,6 +46,7 @@ const routePermissionMap: Record<string, UserRole[]> = {
   users: ['admin'],
   'data-permission': ['admin', 'dba'],
   'audit-rules': ['admin', 'dba'],
+  'audit-logs': ['admin', 'dba'],
   workflow: ['admin', 'dba'],
   'auto-task': ['admin'],
   announcement: ['admin'],