Function start_tear_off_tracking 

pub fn start_tear_off_tracking(
    state: Arc<AppState>,
    source_label: String,
    dragged_label: String,
    tab_id: String,
    source_ws_id: String,
    dest_ws_id: String,
    original_tab_index: usize,
    was_pinned: bool,
) -> Result<(), String>

Spawn a hook thread for the duration of a tear-off gesture. Returns Ok once the hook is installed; the thread runs in the background until WM_LBUTTONUP arrives or stop_tear_off_tracking is called.

Safe to call from a Tokio worker thread — the hook thread is independent and runs its own message loop.