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-network-app/node_modules/browserslist/browser.js

@@ -0,0 +1,54 @@
+var BrowserslistError = require('./error')
+
+function noop() {}
+
+module.exports = {
+  loadQueries: function loadQueries() {
+    throw new BrowserslistError(
+      'Sharable configs are not supported in client-side build of Browserslist'
+    )
+  },
+
+  getStat: function getStat(opts) {
+    return opts.stats
+  },
+
+  loadConfig: function loadConfig(opts) {
+    if (opts.config) {
+      throw new BrowserslistError(
+        'Browserslist config are not supported in client-side build'
+      )
+    }
+  },
+
+  loadCountry: function loadCountry() {
+    throw new BrowserslistError(
+      'Country statistics are not supported ' +
+        'in client-side build of Browserslist'
+    )
+  },
+
+  loadFeature: function loadFeature() {
+    throw new BrowserslistError(
+      'Supports queries are not available in client-side build of Browserslist'
+    )
+  },
+
+  currentNode: function currentNode(resolve, context) {
+    return resolve(['maintained node versions'], context)[0]
+  },
+
+  parseConfig: noop,
+
+  readConfig: noop,
+
+  findConfig: noop,
+
+  findConfigFile: noop,
+
+  clearCaches: noop,
+
+  oldDataWarning: noop,
+
+  env: {}
+}