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/imurmurhash/package.json

@@ -0,0 +1,40 @@
+{
+  "name": "imurmurhash",
+  "version": "0.1.4",
+  "description": "An incremental implementation of MurmurHash3",
+  "homepage": "https://github.com/jensyt/imurmurhash-js",
+  "main": "imurmurhash.js",
+  "files": [
+    "imurmurhash.js",
+    "imurmurhash.min.js",
+    "package.json",
+    "README.md"
+  ],
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/jensyt/imurmurhash-js"
+  },
+  "bugs": {
+    "url": "https://github.com/jensyt/imurmurhash-js/issues"
+  },
+  "keywords": [
+    "murmur",
+    "murmurhash",
+    "murmurhash3",
+    "hash",
+    "incremental"
+  ],
+  "author": {
+    "name": "Jens Taylor",
+    "email": "jensyt@gmail.com",
+    "url": "https://github.com/homebrewing"
+  },
+  "license": "MIT",
+  "dependencies": {
+  },
+  "devDependencies": {
+  },
+  "engines": {
+    "node": ">=0.8.19"
+  }
+}