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/@babel/helpers/README.md

@@ -0,0 +1,19 @@
+# @babel/helpers
+
+> Collection of helper functions used by Babel transforms.
+
+See our website [@babel/helpers](https://babeljs.io/docs/babel-helpers) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save-dev @babel/helpers
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/helpers --dev
+```