Function setRootPath

src/platforms/stub/fs_stub.hpp:147–153

    ~StubFileSystem() override = default;

    void setRootPath(const fl::string& path) FL_NOEXCEPT {
        mRootPath = path;
        // Ensure the path ends with a directory separator
        if (!mRootPath.empty() && mRootPath.back() != '/' && mRootPath.back() != '\\') {
            mRootPath.append("/");
        }
    }

    // Static test utility functions for file/directory management
    // These are only available on the stub/test platform