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

mcp-server/start-mcp.bat

@@ -0,0 +1,15 @@
+@echo off
+REM Script pour démarrer le serveur MCP Keep Notes
+REM Mode: Stdio (par défaut)
+
+echo.
+echo ==========================================
+echo    🚀 Keep Notes MCP Server
+echo ==========================================
+echo.
+echo Démarrage du serveur MCP en mode Stdio...
+echo Appuyez sur Ctrl+C pour arrêter
+echo.
+
+cd /d "%~dp0"
+node index.js