feat(web): add settings sub-pages and connect to backend APIs

- Add GeneralSettingsPage for language, privacy, and notification settings
- Add FeedbackPage for user feedback submission with image upload
- Connect settings to backend PATCH /users/me/settings API
- Implement language preference sync between frontend and backend
- Update login flow to pass language preference and redirect based on user settings
- Add Astro entry pages for /settings/general and /settings/feedback routes
- Update sidebar navigation: language button links to general settings
- Fix account data card to link to profile page
- Remove "deletion" text from account data description

web/src/components/DashboardAppPage.astro

@@ -17,6 +17,8 @@ const translations = {
   profile: t(locale, 'profile'),
   settings: t(locale, 'settings'),
   divination: t(locale, 'divination'),
+  general: t(locale, 'general'),
+  feedback: t(locale, 'feedback'),
 };
 ---