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>

frontend/src/App.tsx

@@ -34,12 +34,14 @@ const AdminUsersPage = lazy(() => import('./pages/admin/AdminUsersPage').then(m
 const AdminCatalogPage = lazy(() => import('./pages/admin/AdminCatalogPage').then(m => ({ default: m.AdminCatalogPage })));
 const AdminEmailTemplatesPage = lazy(() => import('./pages/admin/AdminEmailTemplatesPage').then(m => ({ default: m.AdminEmailTemplatesPage })));
 const AdminBackupPage = lazy(() => import('./pages/admin/AdminBackupPage').then(m => ({ default: m.AdminBackupPage })));
+const AdminLogsPage = lazy(() => import('./pages/admin/AdminLogsPage').then(m => ({ default: m.AdminLogsPage })));
 
 // Admin mobile screens (lazy-loaded)
 const AdminUsersMobileScreen = lazy(() => import('./features/admin/mobile/AdminUsersMobileScreen').then(m => ({ default: m.AdminUsersMobileScreen })));
 const AdminCatalogMobileScreen = lazy(() => import('./features/admin/mobile/AdminCatalogMobileScreen').then(m => ({ default: m.AdminCatalogMobileScreen })));
 const AdminEmailTemplatesMobileScreen = lazy(() => import('./features/admin/mobile/AdminEmailTemplatesMobileScreen'));
 const AdminBackupMobileScreen = lazy(() => import('./features/admin/mobile/AdminBackupMobileScreen'));
+const AdminLogsMobileScreen = lazy(() => import('./features/admin/mobile/AdminLogsMobileScreen'));
 
 // Admin Community Stations (lazy-loaded)
 const AdminCommunityStationsPage = lazy(() => import('./features/admin/pages/AdminCommunityStationsPage').then(m => ({ default: m.AdminCommunityStationsPage })));
@@ -919,6 +921,31 @@ function App() {
                 </MobileErrorBoundary>
               </motion.div>
             )}
+            {activeScreen === "AdminLogs" && (
+              <motion.div
+                key="admin-logs"
+                initial={{opacity:0, y:8}}
+                animate={{opacity:1, y:0}}
+                exit={{opacity:0, y:-8}}
+                transition={{ duration: 0.2, ease: "easeOut" }}
+              >
+                <MobileErrorBoundary screenName="AdminLogs">
+                  <React.Suspense fallback={
+                    <div className="space-y-4">
+                      <GlassCard>
+                        <div className="p-4">
+                          <div className="text-slate-500 py-6 text-center">
+                            Loading audit logs...
+                          </div>
+                        </div>
+                      </GlassCard>
+                    </div>
+                  }>
+                    <AdminLogsMobileScreen />
+                  </React.Suspense>
+                </MobileErrorBoundary>
+              </motion.div>
+            )}
           </AnimatePresence>
           <DebugInfo />
         </Layout>
@@ -990,6 +1017,7 @@ function App() {
             <Route path="/garage/settings/admin/community-stations" element={<AdminCommunityStationsPage />} />
             <Route path="/garage/settings/admin/email-templates" element={<AdminEmailTemplatesPage />} />
             <Route path="/garage/settings/admin/backup" element={<AdminBackupPage />} />
+            <Route path="/garage/settings/admin/logs" element={<AdminLogsPage />} />
             <Route path="*" element={<Navigate to="/garage/dashboard" replace />} />
           </Routes>
         </RouteSuspense>