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/router/router_config.yaml

@@ -0,0 +1,11 @@
+messaging_inbound:
+  enabled: true
+  source_subject: "agent.filter.decision"
+  target_subject: "router.invoke.agent"
+
+# Future routing rules can be added here
+# e.g., direct invocations, cron jobs, webhooks
+
+
+
+