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

scripts/stop-phase3.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+echo "🛑 Stopping DAARION Phase 3 services..."
+echo ""
+
+docker-compose -f docker-compose.phase3.yml down
+
+echo ""
+echo "✅ Phase 3 services stopped"
+echo ""
+echo "To remove volumes (DB data):"
+echo "  docker-compose -f docker-compose.phase3.yml down -v"
+echo ""
+
+
+
+