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/supports-preserve-symlinks-flag/index.js

@@ -0,0 +1,9 @@
+'use strict';
+
+module.exports = (
+// node 12+
+	process.allowedNodeEnvironmentFlags && process.allowedNodeEnvironmentFlags.has('--preserve-symlinks')
+) || (
+// node v6.2 - v11
+	String(module.constructor._findPath).indexOf('preserveSymlinks') >= 0 // eslint-disable-line no-underscore-dangle
+);