Function install_hooks 

pub fn install_hooks(state: Arc<AppState>)

Phase B.9.1 — install the WRR hooks. Idempotent (logs and returns if hooks are already installed). Must be called from a thread that owns a Win32 message pump — the host’s CEF UI thread does, so we install from there at startup.

Also enumerates the current monitor topology and reports it once. WM_DISPLAYCHANGE wiring for mid-session topology updates is a B.9.2 follow-up.

state is stashed in a static OnceLock so the static callback can read pending_window_creations to supply label_hint.