pnpm has Path Traversal via arbitrary file permission modification

pnpm is a package manager. Prior to version 10.28.2, when pnpm processes a package's `directories.bin` field, it uses `path.join()` without validating the result stays within the package root. A malicious npm package can specify `"directories": {"bin": "../../../../tmp"}` to escape the package directory, causing pnpm to chmod 755 files at arbitrary locations. This issue only affects Unix/Linux/macOS. Windows is not affected (`fixBin` gated by `EXECUTABLE_SHEBANG_SUPPORTED`). Version 10.28.2 contains a patch.