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/eslint/messages/no-config-found.js

@@ -0,0 +1,15 @@
+"use strict";
+
+module.exports = function(it) {
+    const { directoryPath } = it;
+
+    return `
+ESLint couldn't find a configuration file. To set up a configuration file for this project, please run:
+
+    npm init @eslint/config
+
+ESLint looked for configuration files in ${directoryPath} and its ancestors. If it found none, it then looked in your home directory.
+
+If you think you already have a configuration file or if you need more help, please stop by the ESLint Discord server: https://eslint.org/chat
+`.trimStart();
+};