feat(ui): add theme toggle to dashboard layout

- Implement theme switching between light and dark modes
- Use Mantine's color scheme for automatic detection
- Add tooltip for theme toggle button
- Update App component to use 'auto' color scheme

pkg/api/server.go

@@ -103,6 +103,7 @@ func NewServer(cfg *config.Config, db *bun.DB, wh WhatsHookedInterface) (*Server
 	// Setup ResolveSpec routes on the protected /api/v1 subrouter (auto-generated CRUD)
 	restheadspec.SetupMuxRoutes(apiV1Router, handler, nil)
 	apiV1Router.HandleFunc("/system/stats", handleSystemStats).Methods("GET")
+	apiV1Router.HandleFunc("/cache/stats", wh.Handlers().GetCacheStats).Methods("GET")
 
 	// Add custom routes (login, logout, etc.) on main router
 	SetupCustomRoutes(router, secProvider, db)