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/components/layout/AppShell.tsx

@@ -11,6 +11,8 @@ import { PluginRegistry } from '@/components/plugins/PluginRegistry';
 import { AIUIControlIndicator } from '@/components/ai-ui-control/AIUIControlIndicator';
 import { WindowContainer } from '@/components/window/WindowContainer';
 import { ErrorBoundary } from '@/components/ErrorBoundary';
+import { WelcomeDialog } from '@/components/onboarding/WelcomeDialog';
+import { OnboardingTour } from '@/components/onboarding/OnboardingTour';
 
 export function AppShell() {
   const location = useLocation();
@@ -50,6 +52,8 @@ export function AppShell() {
       <AIUIControlIndicator />
       <WindowContainer />
       <ToastContainer />
+      <WelcomeDialog open={false} />
+      <OnboardingTour />
     </div>
   );
 }