New command that generates a comprehensive project summary from completed
milestone artifacts. Designed for team onboarding — new contributors can
run this against a completed project and understand what was built, how,
and why, with optional interactive Q&A grounded in build artifacts.
- commands/gsd/milestone-summary.md: command definition
- get-shit-done/workflows/milestone-summary.md: 9-step workflow
- tests/milestone-summary.test.cjs: 11 tests (command + workflow validation)
- tests/copilot-install.test.cjs: bump expected skill count 53→54
Reads: ROADMAP, REQUIREMENTS, PROJECT, CONTEXT, SUMMARY, VERIFICATION,
RETROSPECTIVE artifacts. Writes to .planning/reports/MILESTONE_SUMMARY-v{X}.md.
Closes#1298
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>