feat: Add presence heartbeat for Matrix online status

- matrix-gateway: POST /internal/matrix/presence/online endpoint
- usePresenceHeartbeat hook with activity tracking
- Auto away after 5 min inactivity
- Offline on page close/visibility change
- Integrated in MatrixChatRoom component

services/node2-rag-router/requirements.txt

@@ -0,0 +1,10 @@
+fastapi>=0.104.0
+uvicorn>=0.24.0
+httpx>=0.25.0
+pydantic>=2.0.0
+qdrant-client>=1.7.0
+pymilvus>=2.3.0
+neo4j>=5.14.0
+
+
+