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/@nodelib/fs.stat/out/index.d.ts

@@ -0,0 +1,12 @@
+import type { FileSystemAdapter, StatAsynchronousMethod, StatSynchronousMethod } from './adapters/fs';
+import * as async from './providers/async';
+import Settings, { Options } from './settings';
+import type { Stats } from './types';
+declare type AsyncCallback = async.AsyncCallback;
+declare function stat(path: string, callback: AsyncCallback): void;
+declare function stat(path: string, optionsOrSettings: Options | Settings, callback: AsyncCallback): void;
+declare namespace stat {
+    function __promisify__(path: string, optionsOrSettings?: Options | Settings): Promise<Stats>;
+}
+declare function statSync(path: string, optionsOrSettings?: Options | Settings): Stats;
+export { Settings, stat, statSync, AsyncCallback, FileSystemAdapter, StatAsynchronousMethod, StatSynchronousMethod, Options, Stats };