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/estraverse/.jshintrc

@@ -0,0 +1,16 @@
+{
+  "curly": true,
+  "eqeqeq": true,
+  "immed": true,
+  "eqnull": true,
+  "latedef": true,
+  "noarg": true,
+  "noempty": true,
+  "quotmark": "single",
+  "undef": true,
+  "unused": true,
+  "strict": true,
+  "trailing": true,
+
+  "node": true
+}