feat: dev env bootstrap, deferred sessions, and mock agent fallback

- Add dotenv loader for NODE_ENV=development with .env.development.example
- Add factory self-hosting deployment docs
- Defer agent session creation in handoff init (create on first prompt)
- Fall back to mock agent when Claude/Codex credentials are missing
- Replace stub mock agent launcher with real ACP JSON-RPC Node.js script
- Fix React useEffect dependency array in org settings
- Clean up tracked .context cache/temp files

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/docs.json

@@ -57,6 +57,7 @@
 								"icon": "server",
 								"pages": [
 									"deploy/local",
+									"deploy/factory-self-hosting",
 									"deploy/computesdk",
 									"deploy/e2b",
 									"deploy/daytona",