docs: document Agent Sessions Hub, Timeline, and API endpoints
Add comprehensive documentation for recent feature additions:
- Agent Sessions Hub (/sessions): Epic-grouped task feed, cross-agent
communication, productivity metrics, and derived activity engine
- Timeline feature (/timeline): Real-time chronological activity feed
- Complete API reference for all endpoints including agent coordination,
sessions management, activity streaming, and bead operations
Updated README.md with new feature sections and links.
Covers commits from the last 5 days including:
- feat(skills): beadboard-driver skill (1ae7efb)
- feat(observability): timeline and agent productivity APIs (bfe4f85)
- feat(ui): Social-Dense Agent Sessions Hub (f3558dc)
- feat(logic): derived-activity engine and agent-session protocols (ab05195)
Co-Authored-By: Warp <agent@warp.dev>
4251bd144b