- Add priority_sequence_test.dart: 29 tests covering full priority chain
  (maintenance > force > optional), single-overlay rule, rapid-fire bursts,
  navigator-key timing, skip-version interactions, dialog/sheet variants
- Add live_rc_test.dart: live Firebase RC end-to-end tests using real
  network — credentials injected via --dart-define (no key in source)
- Add tool/set_remote_config.dart: dev script for pushing RC test payloads
- Update .pubignore: exclude tool/, live_rc_test.dart (project-specific),
  and firebase_options.dart/google-services.json from published package