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/isexe/package.json

@@ -0,0 +1,31 @@
+{
+  "name": "isexe",
+  "version": "2.0.0",
+  "description": "Minimal module to check if a file is executable.",
+  "main": "index.js",
+  "directories": {
+    "test": "test"
+  },
+  "devDependencies": {
+    "mkdirp": "^0.5.1",
+    "rimraf": "^2.5.0",
+    "tap": "^10.3.0"
+  },
+  "scripts": {
+    "test": "tap test/*.js --100",
+    "preversion": "npm test",
+    "postversion": "npm publish",
+    "postpublish": "git push origin --all; git push origin --tags"
+  },
+  "author": "Isaac Z. Schlueter <i@izs.me> (http://blog.izs.me/)",
+  "license": "ISC",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/isaacs/isexe.git"
+  },
+  "keywords": [],
+  "bugs": {
+    "url": "https://github.com/isaacs/isexe/issues"
+  },
+  "homepage": "https://github.com/isaacs/isexe#readme"
+}