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/locales/en.json

@@ -27,6 +27,14 @@
     "sendResetLink": "Send Reset Link",
     "backToLogin": "Back to login"
   },
+  "sidebar": {
+    "notes": "Notes",
+    "reminders": "Reminders",
+    "labels": "Labels",
+    "editLabels": "Edit labels",
+    "archive": "Archive",
+    "trash": "Trash"
+  },
   "notes": {
     "title": "Notes",
     "newNote": "New note",
@@ -531,4 +539,4 @@
     "moveToNotebook": "Move to notebook",
     "generalNotes": "General Notes"
   }
-}
+}