fix: 修复聊天系统编译错误

- 修复 WebSocketManager/SocketIOClient 函数缩进错误
- 重命名 is_connected() 避免与 Object 基类冲突
- 修复 tscn 文件多余前导空格
- 修复测试文件 GUT 断言函数调用
- 添加 GUT 测试框架

addons/gut/gui/run_from_editor.gd

@@ -0,0 +1,19 @@
+# ------------------------------------------------------------------------------
+# This is the entry point when running tests from the editor.
+#
+# This script should conform to, or ignore, the strictest warning settings.
+# ------------------------------------------------------------------------------
+extends Node2D
+
+var GutLoader : Object
+
+func _init() -> void:
+	GutLoader = load("res://addons/gut/gut_loader.gd")
+
+
+@warning_ignore("unsafe_method_access")
+func _ready() -> void:
+	var runner : Node = load("res://addons/gut/gui/GutRunner.tscn").instantiate()
+	add_child(runner)
+	runner.run_from_editor()
+	GutLoader.restore_ignore_addons()