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/is-core-module/.eslintrc

@@ -0,0 +1,18 @@
+{
+    "extends": "@ljharb",
+    "root": true,
+    "rules": {
+		"func-style": 1,
+    },
+    "overrides": [
+        {
+            "files": "test/**",
+            "rules": {
+                "global-require": 0,
+				"max-depth": 0,
+                "max-lines-per-function": 0,
+				"no-negated-condition": 0,
+            },
+        },
+    ],
+}