类：RealFSProvider

🌐 Class: RealFSProvider

一个提供者，它封装一个目录（即实际文件系统上的目录），并通过 VFS API 暴露其内容。所有 VFS 路径都是相对于根目录解析的，并且会验证是否保持在根目录内；解析到根目录外的符号链接会被拒绝。这种路径映射不是沙箱或访问控制机制。

🌐 A provider that wraps a directory (i.e. one on the actual file system) and exposes its contents through the VFS API. All VFS paths are resolved relative to the root and verified to stay inside it; symbolic links resolving outside the root are rejected. This path mapping is not a sandbox or access-control mechanism.