Function laminar_subscribe_callback 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn laminar_subscribe_callback(
    conn: *mut LaminarConnection,
    query: *const c_char,
    on_data: LaminarSubscriptionCallback,
    on_error: LaminarErrorCallback,
    user_data: *mut c_void,
    out: *mut *mut LaminarSubscriptionHandle,
) -> i32

Create a callback-based subscription; on_data is called from a background thread.

Safety

conn, query, and out must be valid non-null pointers; query must be a null-terminated UTF-8 string; callbacks must be thread-safe if user_data is shared.