v1.4.7: bring CONTRIBUTING.md up to date — state the feature freeze up front (bug fixes/hardening/tests/docs wanted, feature MRs declined for now), require all three test suites green (test_deflock.py, test_update.sh, test_install.sh) plus the dev/run.sh tour for diff/guard/churn changes, document the dev/ fake-Overpass environment as the no-secrets way to develop, and mention ntfy alongside Discord; every command and expected output cited was re-verified against the repo Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>