Function moq_client_set_tls_key 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn moq_client_set_tls_key(
    client: u32,
    path: *const c_char,
    path_len: usize,
) -> i32

Present this PEM private key when the relay requires mTLS.

Only the private key is read from the file; any certificates in it are ignored. Must be paired with moq_client_set_tls_cert or the connect fails. A NULL or empty path clears it.

Returns zero on success, or a negative code if the handle is unknown.

Safety

• The caller must ensure that path is NULL or a valid pointer to path_len bytes.