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/constants.d.ts

@@ -0,0 +1,4 @@
+/**
+ * IS `true` for Node.js 10.10 and greater.
+ */
+export declare const IS_SUPPORT_READDIR_WITH_FILE_TYPES: boolean;