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/react-dom/server.browser.js

@@ -0,0 +1,17 @@
+'use strict';
+
+var l, s;
+if (process.env.NODE_ENV === 'production') {
+  l = require('./cjs/react-dom-server-legacy.browser.production.min.js');
+  s = require('./cjs/react-dom-server.browser.production.min.js');
+} else {
+  l = require('./cjs/react-dom-server-legacy.browser.development.js');
+  s = require('./cjs/react-dom-server.browser.development.js');
+}
+
+exports.version = l.version;
+exports.renderToString = l.renderToString;
+exports.renderToStaticMarkup = l.renderToStaticMarkup;
+exports.renderToNodeStream = l.renderToNodeStream;
+exports.renderToStaticNodeStream = l.renderToStaticNodeStream;
+exports.renderToReadableStream = s.renderToReadableStream;