feat: add llms.txt standard support for AI agent discoverability (#784)

Cherry-picked website/, scripts/generate-llms-full.sh, and deploy-docs.yml
from joyshmitz's PR. Fixed workflow to trigger on main branch instead of
docs/docusaurus-site.

Features:
- Docusaurus documentation site with llms.txt support
- Environment-variable driven config (defaults to steveyegge org)
- Automated llms-full.txt generation from docs
- GitHub Pages deployment workflow

Co-authored-by: joyshmitz <joyshmitz@users.noreply.github.com>

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Executed-By: beads/crew/dave
Rig: beads
Role: crew

website/docs/multi-agent/index.md

@@ -0,0 +1,72 @@
+---
+id: index
+title: Multi-Agent
+sidebar_position: 1
+---
+
+# Multi-Agent Coordination
+
+Beads supports coordination between multiple AI agents and repositories.
+
+## Overview
+
+Multi-agent features enable:
+- **Routing** - Automatic issue routing to correct repositories
+- **Cross-repo dependencies** - Dependencies across repository boundaries
+- **Agent coordination** - Work assignment and handoff between agents
+
+## Key Concepts
+
+### Routes
+
+Routes define which repository handles which issues:
+
+```jsonl
+{"pattern": "frontend/*", "target": "frontend-repo"}
+{"pattern": "backend/*", "target": "backend-repo"}
+{"pattern": "*", "target": "main-repo"}
+```
+
+### Work Assignment
+
+Pin work to specific agents:
+
+```bash
+bd pin bd-42 --for agent-1 --start
+bd hook --agent agent-1  # Show pinned work
+```
+
+### Cross-repo Dependencies
+
+Track dependencies across repositories:
+
+```bash
+bd dep add bd-42 external:other-repo/bd-100
+```
+
+## Architecture
+
+```
+┌─────────────────┐
+│   Main Repo     │
+│   (coordinator) │
+└────────┬────────┘
+         │ routes
+    ┌────┴────┐
+    │         │
+┌───▼───┐ ┌───▼───┐
+│Frontend│ │Backend│
+│ Repo   │ │ Repo  │
+└────────┘ └────────┘
+```
+
+## Getting Started
+
+1. **Single repo**: Standard beads workflow
+2. **Multi-repo**: Configure routes and cross-repo deps
+3. **Multi-agent**: Add work assignment and handoff
+
+## Navigation
+
+- [Routing](/multi-agent/routing) - Auto-routing configuration
+- [Coordination](/multi-agent/coordination) - Agent coordination patterns