Quick Chat model changes now settle in target order, the remote probe uses one deadline, and node-owned Codex child shutdown is acknowledged and bounded. Related: #123420
* fix(macos): gate remote onboarding on gateway auth * fix(macos): address onboarding CI failures * test(macos): stabilize gateway auth routing coverage * fix(macos): bound remote gateway onboarding probe * fix(macos): satisfy remote probe CI guards * fix(macos): scope remote probe cleanup ownership * refactor(macos): remove unused health snapshot wrapper