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。

docs/README.md

@@ -0,0 +1,56 @@
+# Project Structure Documentation
+
+This document outlines the recommended structure for the Interface Automation Test project. A well-organized structure promotes maintainability, scalability, and collaboration.
+
+## Directory Structure
+
+Here is the proposed optimized directory structure:
+
+```
+/
+|-- core/                  # Main source code
+|   |-- api.py
+|   |-- main.py
+|   |-- luffy.py
+|   +-- ...
+|
+|-- tests/                 # Test cases
+|   |-- a_test_case.py
+|   +-- ...
+|
+|-- config/                # Configuration files
+|   |-- id.yaml
+|   |-- extract.yaml
+|   +-- ...
+|
+|-- utils/                 # Utility modules
+|
+|-- docs/                  # Project documentation
+|   +-- README.md
+|
+|-- .gitignore             # Git ignore file
+|-- pytest.ini             # Pytest configuration
+|-- pyproject.toml         # Python project configuration
+|-- README.md              # Main project README
+```
+
+## Description of Directories
+
+*   **`core/`**: This directory contains the core application logic for the interface tests. Files like `api.py`, `main.py`, and `luffy.py` which handle the main business logic should reside here.
+
+*   **`tests/`**: This directory is for all the automated tests. Each test file should ideally correspond to a module or a feature.
+
+*   **`config/`**: This directory should store all configuration files, such as `id.yaml` and `extract.yaml`. This separation makes it easier to manage different environments (e.g., development, staging, production).
+
+*   **`utils/`**: This directory holds common utility functions and helper scripts that can be used across different parts of the project.
+
+*   **`docs/`**: This directory contains all project-related documentation, including this structure guide.
+
+## Benefits of this Structure
+
+*   **Clarity**: A clear separation of concerns makes it easy to find code.
+*   **Maintainability**: Easier to maintain and refactor code without affecting other parts of the system.
+*   **Scalability**: The structure can easily scale as the project grows in complexity.
+*   **Collaboration**: New developers can quickly understand the project layout and start contributing.
+
+We recommend moving the existing files into this new structure to improve the overall quality of the project.