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/source-map-js/source-map.js

@@ -0,0 +1,8 @@
+/*
+ * Copyright 2009-2011 Mozilla Foundation and contributors
+ * Licensed under the New BSD license. See LICENSE.txt or:
+ * http://opensource.org/licenses/BSD-3-Clause
+ */
+exports.SourceMapGenerator = require('./lib/source-map-generator').SourceMapGenerator;
+exports.SourceMapConsumer = require('./lib/source-map-consumer').SourceMapConsumer;
+exports.SourceNode = require('./lib/source-node').SourceNode;