fix(exchange,case_validator),refactor(),feat(model): 解决 Pydantic 模型初始化与变量占位符的类型冲突,优化变量替换逻辑,重构 CaseInfo 模型并引入延迟校验机制

- 引入 SmartInt 和 SmartDict 类型，支持 YAML 占位符与业务类型的自动转换。
- 优化 CaseInfo 互斥校验逻辑，确保 request 与 api_action 二选一。
- 统一使用 Pydantic V2 的 model_config 规范。
- 将变量替换时机提前至模型实例化之前，支持占位符在校验前完成真实值注入，
保证了 int/bool 等字段的类型转换正确性。
- 优化断言渲染时机，支持响应提取值关联。

test_cases/request_model_test.yaml

@@ -0,0 +1,36 @@
+feature: 页面状态
+story: 状态
+title: 查询状态信息
+epic: 的点点滴滴
+request:
+  method: get
+  url: /answer/api/v1/connector/info
+  headers:
+    Host: 119.91.19.171:40065
+    Accept-Language: en_US
+    Accept: application/json, text/plain, */*
+    User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36 Edg/131.0.0.0
+    Referer: http://119.91.19.171:40065/users/login
+    Accept-Encoding: gzip, deflate
+extract: # 提取变量
+  msg:
+    - "json"
+    - "$.msg"
+    - 0
+
+validate:
+  - check: status_code    # 检查的对象（或是变量名）
+    assert: equals        # 断言方法
+    expect: 200           # 期望值
+    msg: "校验接口状态码"   # 描述（可选）
+
+  - check: $.msg
+    assert: contains
+    expect: "Success"
+    msg: "检查返回消息"
+parametrize: # 数据驱动测试
+  - [ "title","username","password","msg" ] # 变量名
+  - [ "测试1","user1","pass1","200" ] # 变量值
+  - [ "测试2","user2","pass2","300" ] # 变量值
+  - [ "测试3","user3","pass3","200" ] # 变量值
+  - [ "测试4","user4","pass4","200" ] # 变量值