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/pages/zh/settings/general.astro

@@ -0,0 +1,23 @@
+---
+import App from '../../../layouts/App.astro';
+import DashboardApp from '../../../components/DashboardApp';
+import { t } from '../../../i18n/utils';
+
+const locale = 'zh' as const;
+const translations = {
+  dashboard: t(locale, 'dashboard'),
+  store: t(locale, 'store'),
+  pricing: t(locale, 'pricing'),
+  history: t(locale, 'history'),
+  notifications: t(locale, 'notifications'),
+  profile: t(locale, 'profile'),
+  settings: t(locale, 'settings'),
+  divination: t(locale, 'divination'),
+  general: t(locale, 'general'),
+  feedback: t(locale, 'feedback'),
+};
+---
+
+<App locale={locale}>
+  <DashboardApp client:only="react" locale={locale} translations={translations} />
+</App>