fix(uninstall): escalate to SIGTERM/SIGKILL after Quit ignored

After the graceful Quit Apple Event, restore the kill ladder so apps
that ignore the Apple Event do not keep running after "Uninstall
complete". The user has already confirmed removal, so a still-running
process at that point blocks a clean result; trading unsaved state for
that result is the explicit ask.

The escalation is gated:
- Skips entirely if the graceful Quit lands during the poll window.
- pkill SIGTERM with a 2s recovery window.
- pkill -9 SIGKILL with a 2s recovery window.
- One sudo pkill -9 retry only when non-interactive sudo is already
  cached (no new prompt under MOLE_TEST_NO_AUTH / MOLE_TEST_MODE).
- Three 1s polls at the end for apps mid-fsync.

This intentionally diverges from the Mac app, which kept the kill-free
behavior. Tests cover both paths: clean exit through graceful Quit, and
escalation when Quit does not land.