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>
