Add comprehensive architectural documentation for the migration race condition fix, including: - ADR-022: Architectural decision record for the fix - migration-race-condition-answers.md: All 23 Q&A answered - migration-fix-quick-reference.md: Implementation checklist - migration-race-condition-fix-implementation.md: Detailed guide These documents guided the implementation in v1.0.0-rc.5. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>