fix(hotkey): live-update diagnostics + transient state resets

- SaveSettings applies hotkey immediately (no poller dependency) and
  adopts the full saved config, syncing watcher mtime so the poller
  skips the already-applied save
- Helper: reset hook transient state on config reload (stale
  CONSUMED_WIN_VK / held mask key made the new combo undetectable)
- nex: clear raw-input Win tracking after live update
- Probes at each detection hop (helper hook/pipe write, nex receive)
  for diagnosing live-update failures