test：增强认证模块测试覆盖

- 添加认证UI自动化测试
- 实现增强型Toast消息测试
- 完善用户交互测试用例
- 提高测试代码覆盖率

tests/auth/auth_ui_test.gd

@@ -403,6 +403,8 @@ func get_expected_ui_feedback(scenario: Dictionary) -> String:
 					return "红色Toast: 登录请求过于频繁"
 				500:
 					return "红色Toast: 服务器繁忙"
+				503:
+					return "红色Toast: 系统维护中"
 		"send_code":
 			match response_code:
 				200, 206:
@@ -413,8 +415,38 @@ func get_expected_ui_feedback(scenario: Dictionary) -> String:
 					return "红色Toast: 请求过于频繁"
 				500:
 					return "红色Toast: 服务器繁忙"
+				503:
+					return "红色Toast: 系统维护中"
 				0:
 					return "红色Toast: 网络连接失败"
+		"send_login_code":
+			match response_code:
+				200, 206:
+					return "绿色Toast: 登录验证码已发送"
+				400:
+					return "红色Toast: 邮箱或手机号格式错误"
+				404:
+					return "红色Toast: 用户不存在"
+				429:
+					return "红色Toast: 请求过于频繁"
+				500:
+					return "红色Toast: 服务器繁忙"
+				503:
+					return "红色Toast: 系统维护中"
+		"verification_code_login":
+			match response_code:
+				200:
+					return "绿色Toast: 验证码登录成功，跳转到主场景"
+				401:
+					return "红色Toast: 验证码错误或已过期"
+				404:
+					return "红色Toast: 用户不存在"
+				429:
+					return "红色Toast: 请求过于频繁"
+				500:
+					return "红色Toast: 服务器繁忙"
+				503:
+					return "红色Toast: 系统维护中"
 		"verify_email":
 			match response_code:
 				200:
@@ -425,6 +457,8 @@ func get_expected_ui_feedback(scenario: Dictionary) -> String:
 					return "红色Toast: 请先获取验证码"
 				500:
 					return "红色Toast: 验证失败"
+				503:
+					return "红色Toast: 系统维护中"
 		"register":
 			match response_code:
 				201:
@@ -437,6 +471,8 @@ func get_expected_ui_feedback(scenario: Dictionary) -> String:
 					return "红色Toast: 注册请求过于频繁，请稍后再试"
 				500:
 					return "红色Toast: 注册失败"
+				503:
+					return "红色Toast: 系统维护中"
 	
 	return "未知响应"