Function socket_path 

pub fn socket_path(label: &str) -> Result<PathBuf, ServiceError>

Derive the IPC socket path for a given service label.

• Linux: $XDG_RUNTIME_DIR/{label}.sock (fallback: /run/user/{uid}/{label}.sock)
• macOS: /tmp/{label}.sock
• Windows: \\.\pipe\{label}

Errors

Returns ServiceError::Init if the label is empty, contains path separators, or contains .. components.