Fixes#985
- Create src/brain/__init__.py and src/brain/worker.py with DistributedWorker
- DistributedWorker routes tasks to three backends:
- agentic_loop: local multi-step execution (default)
- kimi: heavy research via Gitea kimi-ready issues (when gitea_enabled + exceeds_local_capacity)
- paperclip: task submission via Paperclip API (when paperclip_api_key configured)
- Implements task lifecycle: queued → running → completed | failed
- Auto-retry with exponential fallback (MAX_RETRIES=2) on failure
- delegate_task now returns real task_id instead of None/"noted"
- Add brain package to pyproject.toml packages list
- Add 32 unit tests covering task submission, routing, lifecycle, and integration
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
