- Add 12 cross-project instruction files to resources/instructions/
- Add cleanup-copilot-history.mjs/.sh: quarantine-based history cleanup with dry-run and aggressive scope
- Add restore-copilot-history.mjs/.sh: restore from quarantine by run, path, or filter
- Add purge-copilot-history-quarantine.mjs/.sh: purge old quarantine runs with keep-latest guard
- Add copilot-history-maintenance.test.mjs: 3 passing unit tests covering all three scripts