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

node-network-app/node_modules/resolve/test/resolver/dot_main/index.js

@@ -0,0 +1 @@
+module.exports = 1;

node-network-app/node_modules/resolve/test/resolver/dot_main/package.json

@@ -0,0 +1,3 @@
+{
+    "main": "."
+}