feat(prd-1): complete M9 - documentation & upstream merge validation
- Created docs/forgejo.md: comprehensive setup guide (prerequisites,
quick start, platform detection, GitHub differences, CI workflows,
upstream merge process, known limitations, troubleshooting)
- Updated README.md with Forgejo support mention and docs link
- Updated CLAUDE.md with Forgejo architecture section
- Added platform input to docs/usage.md inputs table
- Added 5 Forgejo FAQ entries to docs/faq.md
- Upstream merge validated: zero conflicts (based on latest upstream)
- PRD #1 100% complete: all milestones M1-M9 done, 794 tests passing
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
