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_modules/hasown/index.js

@@ -0,0 +1,8 @@
+'use strict';
+
+var call = Function.prototype.call;
+var $hasOwn = Object.prototype.hasOwnProperty;
+var bind = require('function-bind');
+
+/** @type {import('.')} */
+module.exports = bind.call(call, $hasOwn);