Phase 4: Webhooks, Backup/Restore UI, Onboarding/Tutorial

- Webhooks Backend: model, schema, service (HMAC-SHA256, httpx), routes, event bus dispatcher, migration 0042
- Webhooks Frontend: SettingsWebhooksPage (CRUD, test button, event multi-select), API client
- Backup/Restore Backend: model, schema, service (pg_dump/pg_restore), routes (admin-only), migration 0043
- Backup/Restore Frontend: SettingsBackupPage (create, list, restore dialog with RESTORE confirmation, auto-refresh)
- Onboarding: OnboardingTour (8 steps, custom CSS overlay), WelcomeDialog, onboardingStore (zustand + localStorage)
- Onboarding integrated into AppShell
- Routes: /settings/webhooks, /settings/backup registered
- Settings nav: Webhooks, Backup & Restore entries added
- Migration conflict fixed: 0042_webhooks → 0043_backups chain

frontend/src/routes/index.tsx

@@ -58,6 +58,8 @@ const ImportExportPage = React.lazy(() => import('@/pages/ImportExport').then(m
 const TagsPage = React.lazy(() => import('@/pages/Tags').then(m => ({ default: m.TagsPage })));
 const CustomFieldsPage = React.lazy(() => import('@/pages/CustomFields').then(m => ({ default: m.CustomFieldsPage })));
 const ActivityTimelinePage = React.lazy(() => import('@/pages/ActivityTimeline').then(m => ({ default: m.ActivityTimelinePage })));
+const SettingsWebhooksPage = React.lazy(() => import('@/pages/SettingsWebhooks').then(m => ({ default: m.SettingsWebhooksPage })));
+const SettingsBackupPage = React.lazy(() => import('@/pages/SettingsBackup').then(m => ({ default: m.SettingsBackupPage })));
 
 /** Centered spinner fallback for lazy-loaded routes */
 function PageLoader() {
@@ -161,6 +163,8 @@ const router = createBrowserRouter([
           { path: 'ai-settings', element: withSuspense(<SettingsAIPage />) },
           { path: 'menu', element: withSuspense(<SettingsMenuOrderPage />) },
           { path: 'custom-fields', element: withSuspense(<CustomFieldsPage />) },
+          { path: 'webhooks', element: withSuspense(<SettingsWebhooksPage />) },
+          { path: 'backup', element: withSuspense(<SettingsBackupPage />) },
           { path: '*', element: <PluginRouteRenderer /> },
         ],
       },