Add comprehensive backend features and mobile UI improvements

Backend:
- Add 2FA authentication with TOTP support
- Add API keys management system
- Add audit logging for security events
- Add file upload/management system
- Add notifications system with preferences
- Add session management
- Add webhooks integration
- Add analytics endpoints
- Add export functionality
- Add password policy enforcement
- Add new database migrations for core tables

Frontend:
- Add module position system (top/bottom sidebar sections)
- Add search and notifications module configuration tabs
- Add mobile logo replacing hamburger menu
- Center page title absolutely when no tabs present
- Align sidebar footer toggles with navigation items
- Add lighter icon color in dark theme for mobile
- Add API keys management page
- Add notifications page with context
- Add admin analytics and audit logs pages

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

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

frontend/src/modules/index.ts

@@ -32,6 +32,24 @@ export const appModules: ModuleCategory[] = [
         enabled: true,
         requiresAuth: true,
       },
+      {
+        id: 'search',
+        name: 'sidebar.search',
+        icon: 'search',
+        path: '/search',
+        component: null,
+        enabled: true,
+        requiresAuth: true,
+      },
+      {
+        id: 'notifications',
+        name: 'sidebar.notifications',
+        icon: 'notifications',
+        path: '/notifications',
+        component: null,
+        enabled: true,
+        requiresAuth: true,
+      },
       {
         id: 'feature1',
         name: 'sidebar.feature1',