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/components/favorites-section.tsx

@@ -44,7 +44,7 @@ export function FavoritesSection({ pinnedNotes, onEdit }: FavoritesSectionProps)
 
       {/* Collapsible Content */}
       {!isCollapsed && (
-        <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-4">
+        <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-6">
           {pinnedNotes.map((note) => (
             <NoteCard
               key={note.id}