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.scandir/out/providers/sync.d.ts

@@ -0,0 +1,5 @@
+import type Settings from '../settings';
+import type { Entry } from '../types';
+export declare function read(directory: string, settings: Settings): Entry[];
+export declare function readdirWithFileTypes(directory: string, settings: Settings): Entry[];
+export declare function readdir(directory: string, settings: Settings): Entry[];