Add the Config view: edit and save the settings, applied without a restart

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

cmd/arr-tui/main.go

@@ -46,5 +46,11 @@ func run() error {
 		fmt.Fprintln(os.Stderr, "warning:", w)
 	}
 
-	return ui.New(cfg).Run()
+	raw, err := config.LoadFile(*path)
+	if err != nil {
+		return err
+	}
+	app := ui.New(cfg)
+	app.SetConfigSource(*path, raw)
+	return app.Run()
 }