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/package.json

@@ -10,7 +10,12 @@
     "db:generate": "prisma generate",
     "test": "playwright test",
     "test:ui": "playwright test --ui",
-    "test:headed": "playwright test --headed"
+    "test:headed": "playwright test --headed",
+    "test:unit": "vitest run",
+    "test:unit:watch": "vitest watch",
+    "test:unit:coverage": "vitest run --coverage",
+    "test:migration": "vitest run tests/migration",
+    "test:migration:watch": "vitest watch tests/migration"
   },
   "dependencies": {
     "@ai-sdk/openai": "^3.0.7",
@@ -75,10 +80,12 @@
     "@types/nodemailer": "^7.0.4",
     "@types/react": "^19",
     "@types/react-dom": "^19",
+    "@vitest/coverage-v8": "^2.1.9",
     "prisma": "^5.22.0",
     "tailwindcss": "^4.0.0",
     "tsx": "^4.21.0",
     "tw-animate-css": "^1.4.0",
-    "typescript": "^5"
+    "typescript": "^5",
+    "vitest": "^2.1.9"
   }
 }