[Feature] Enhanced Path Validation & Exclusion Mechanism / 增强路径验证与排除机制

[SunYanbox]

1. Intercept AI attempts to read private files like .env

2. Load .gitignore directories as default exclusion list for glob and other search tools

3. Refactor path permission system into standalone module

4. AI尝试读取.env等隐私文件时需要拦截

5. 需要默认加载.gitignore内的目录作为glob和其他search工具的默认排除目录

6. 需要整理路径权限体系为独立系统