Add offline RefreshPrices, fix sync bugs, implement auto-restart

- Implement RefreshPrices for local-first mode
  - Update prices from local_components.current_price cache
  - Graceful degradation when component not found
  - Add PriceUpdatedAt timestamp to LocalConfiguration model
  - Support both authenticated and no-auth price refresh

- Fix sync duplicate entry bug
  - pushConfigurationUpdate now ensures server_id exists before update
  - Fetch from LocalConfiguration.ServerID or search on server if missing
  - Update local config with server_id after finding

- Add application auto-restart after settings save
  - Implement restartProcess() using syscall.Exec
  - Setup handler signals restart via channel
  - Setup page polls /health endpoint and redirects when ready
  - Add "Back" button on setup page when settings exist

- Fix setup handler password handling
  - Use PasswordEncrypted field consistently
  - Support empty password by using saved value

- Improve sync status handling
  - Add fallback for is_offline check in SyncStatusPartial
  - Enhance background sync logging with prefixes

- Update CLAUDE.md documentation
  - Mark Phase 2.5 tasks as complete
  - Add UI Improvements section with future tasks
  - Update SQLite tables documentation

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

cmd/server/main.go

@@ -195,7 +195,9 @@ func setConfigDefaults(cfg *config.Config) {
 
 // runSetupMode starts a minimal server that only serves the setup page
 func runSetupMode(local *localdb.LocalDB) {
-	setupHandler, err := handlers.NewSetupHandler(local, "web/templates")
+	restartSig := make(chan struct{}, 1)
+
+	setupHandler, err := handlers.NewSetupHandler(local, "web/templates", restartSig)
 	if err != nil {
 		slog.Error("failed to create setup handler", "error", err)
 		os.Exit(1)
@@ -242,9 +244,21 @@ func runSetupMode(local *localdb.LocalDB) {
 
 	quit := make(chan os.Signal, 1)
 	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
-	<-quit
 
-	slog.Info("setup mode server stopped")
+	select {
+	case <-quit:
+		slog.Info("setup mode server stopped")
+	case <-restartSig:
+		slog.Info("restarting application with saved settings...")
+
+		// Graceful shutdown
+		ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+		defer cancel()
+		srv.Shutdown(ctx)
+
+		// Restart process with same arguments
+		restartProcess()
+	}
 }
 
 func setupLogger(cfg config.LoggingConfig) {
@@ -336,8 +350,8 @@ func setupRouter(db *gorm.DB, cfg *config.Config, local *localdb.LocalDB, dbUser
 		return nil, nil, fmt.Errorf("creating sync handler: %w", err)
 	}
 
-	// Setup handler (for reconfiguration)
-	setupHandler, err := handlers.NewSetupHandler(local, "web/templates")
+	// Setup handler (for reconfiguration) - no restart signal in normal mode
+	setupHandler, err := handlers.NewSetupHandler(local, "web/templates", nil)
 	if err != nil {
 		return nil, nil, fmt.Errorf("creating setup handler: %w", err)
 	}
@@ -620,6 +634,26 @@ func setupRouter(db *gorm.DB, cfg *config.Config, local *localdb.LocalDB, dbUser
 	return router, syncService, nil
 }
 
+// restartProcess restarts the current process with the same arguments
+func restartProcess() {
+	executable, err := os.Executable()
+	if err != nil {
+		slog.Error("failed to get executable path", "error", err)
+		os.Exit(1)
+	}
+
+	args := os.Args
+	env := os.Environ()
+
+	slog.Info("executing restart", "executable", executable, "args", args)
+
+	err = syscall.Exec(executable, args, env)
+	if err != nil {
+		slog.Error("failed to restart process", "error", err)
+		os.Exit(1)
+	}
+}
+
 func requestLogger() gin.HandlerFunc {
 	return func(c *gin.Context) {
 		start := time.Now()