fix: unify theme system - fix theme switching persistence

- Unified localStorage key to 'theme-preference' across all components
- Fixed header.tsx using wrong localStorage key ('theme' instead of 'theme-preference')
- Added localStorage hybrid persistence for instant theme changes
- Removed router.refresh() which was causing stale data revert
- Replaced Blue theme with Sepia
- Consolidated auth() calls to prevent race conditions
- Updated UserSettingsData types to include all themes

keep-notes/prisma/client-generated/wasm.js

@@ -272,7 +272,10 @@ exports.Prisma.UserAISettingsScalarFieldEnum = {
   preferredLanguage: 'preferredLanguage',
   fontSize: 'fontSize',
   demoMode: 'demoMode',
-  showRecentNotes: 'showRecentNotes'
+  showRecentNotes: 'showRecentNotes',
+  emailNotifications: 'emailNotifications',
+  desktopNotifications: 'desktopNotifications',
+  anonymousAnalytics: 'anonymousAnalytics'
 };
 
 exports.Prisma.SortOrder = {