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/@isaacs/cliui/index.mjs

@@ -0,0 +1,14 @@
+// Bootstrap cliui with ESM dependencies:
+import { cliui } from './build/lib/index.js'
+
+import stringWidth from 'string-width'
+import stripAnsi from 'strip-ansi'
+import wrap from 'wrap-ansi'
+
+export default function ui (opts) {
+  return cliui(opts, {
+    stringWidth,
+    stripAnsi,
+    wrap
+  })
+}