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/schema.prisma

@@ -216,17 +216,21 @@ model MemoryEchoInsight {
 }
 
 model UserAISettings {
-  userId              String  @id
-  titleSuggestions    Boolean @default(true)
-  semanticSearch      Boolean @default(true)
-  paragraphRefactor   Boolean @default(true)
-  memoryEcho          Boolean @default(true)
-  memoryEchoFrequency String  @default("daily")
-  aiProvider          String  @default("auto")
-  preferredLanguage   String  @default("auto")
-  fontSize            String  @default("medium")
-  demoMode            Boolean @default(false)
-  user                User    @relation(fields: [userId], references: [id], onDelete: Cascade)
+  userId               String  @id
+  titleSuggestions     Boolean @default(true)
+  semanticSearch       Boolean @default(true)
+  paragraphRefactor    Boolean @default(true)
+  memoryEcho           Boolean @default(true)
+  memoryEchoFrequency  String  @default("daily")
+  aiProvider           String  @default("auto")
+  preferredLanguage    String  @default("auto")
+  fontSize             String  @default("medium")
+  demoMode             Boolean @default(false)
+  showRecentNotes      Boolean @default(false)
+  emailNotifications   Boolean @default(false)
+  desktopNotifications Boolean @default(false)
+  anonymousAnalytics   Boolean @default(false)
+  user                 User    @relation(fields: [userId], references: [id], onDelete: Cascade)
 
   @@index([memoryEcho])
   @@index([aiProvider])