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/RunAtCursor.tscn

@@ -0,0 +1,60 @@
+[gd_scene load_steps=3 format=3 uid="uid://0yunjxtaa8iw"]
+
+[ext_resource type="Script" uid="uid://c4gmgdl1xwflw" path="res://addons/gut/gui/RunAtCursor.gd" id="1"]
+[ext_resource type="Texture2D" uid="uid://6wra5rxmfsrl" path="res://addons/gut/gui/arrow.png" id="3"]
+
+[node name="RunAtCursor" type="Control"]
+custom_minimum_size = Vector2(510, 0)
+layout_mode = 3
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+offset_right = 1.0
+offset_bottom = -527.0
+grow_horizontal = 2
+grow_vertical = 2
+size_flags_horizontal = 3
+size_flags_vertical = 3
+script = ExtResource("1")
+
+[node name="HBox" type="HBoxContainer" parent="."]
+layout_mode = 0
+anchor_right = 1.0
+anchor_bottom = 1.0
+size_flags_horizontal = 3
+size_flags_vertical = 3
+
+[node name="LblNoneSelected" type="Label" parent="HBox"]
+visible = false
+layout_mode = 2
+text = "<None>"
+
+[node name="BtnRunScript" type="Button" parent="HBox"]
+layout_mode = 2
+text = "test_test.gd"
+
+[node name="Arrow1" type="TextureButton" parent="HBox"]
+custom_minimum_size = Vector2(24, 0)
+layout_mode = 2
+texture_normal = ExtResource("3")
+stretch_mode = 3
+
+[node name="BtnRunInnerClass" type="Button" parent="HBox"]
+layout_mode = 2
+tooltip_text = "Run all tests in Inner-Test-Class TestAssertNe"
+text = "TestAssertNe"
+
+[node name="Arrow2" type="TextureButton" parent="HBox"]
+custom_minimum_size = Vector2(24, 0)
+layout_mode = 2
+texture_normal = ExtResource("3")
+stretch_mode = 3
+
+[node name="BtnRunMethod" type="Button" parent="HBox"]
+layout_mode = 2
+tooltip_text = "Run test test_fails_with_integers_equal"
+text = "test_fails_with_integers_equal"
+
+[connection signal="pressed" from="HBox/BtnRunScript" to="." method="_on_BtnRunScript_pressed"]
+[connection signal="pressed" from="HBox/BtnRunInnerClass" to="." method="_on_BtnRunInnerClass_pressed"]
+[connection signal="pressed" from="HBox/BtnRunMethod" to="." method="_on_BtnRunMethod_pressed"]