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/fraction.js/examples/tape-measure.js

@@ -0,0 +1,16 @@
+/*
+Fraction.js v5.0.0 10/1/2024
+https://raw.org/article/rational-numbers-in-javascript/
+
+Copyright (c) 2024, Robert Eisele (https://raw.org/)
+Licensed under the MIT license.
+*/
+const Fraction = require('fraction.js');
+
+function closestTapeMeasure(frac) {
+
+    // A tape measure is usually divided in parts of 1/16
+
+    return Fraction(frac).roundTo("1/16");
+}
+console.log(closestTapeMeasure("1/3")); // 5/16