Implement `extract_action_items()` and `create_gitea_issue()` to close
the research → knowledge → actionable backlog loop.
- LLM extracts 0-5 concrete action items from research reports
- Each item filed as a Gitea issue with labels, source links, evidence
- Labels auto-resolved/created (actionable, kimi-ready, etc.)
- Child issues linked back to source research issue
- `triage_research_report()` orchestrates end-to-end with dry_run support
- 28 unit tests covering extraction, validation, API calls, and graceful degradation
Fixes#977
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
