add server code

package-lock.json

@@ -9,7 +9,8 @@
       "version": "1.0.0",
       "license": "MIT",
       "dependencies": {
-        "express": "^5.1.0"
+        "express": "^5.1.0",
+        "ws": "^8.18.2"
       }
     },
     "node_modules/accepts": {
@@ -811,6 +812,27 @@
       "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
       "integrity": "sha512-l4Sp/DRseor9wL6EvV2+TuQn63dMkPjZ/sp9XkghTEbV9KlPS1xUsZ3u7/IQO4wxtcFB4bgpQPRcR3QCvezPcQ==",
       "license": "ISC"
+    },
+    "node_modules/ws": {
+      "version": "8.18.2",
+      "resolved": "https://registry.npmjs.org/ws/-/ws-8.18.2.tgz",
+      "integrity": "sha512-DMricUmwGZUVr++AEAe2uiVM7UoO9MAVZMDu05UQOaUII0lp+zOzLLU4Xqh/JvTqklB1T4uELaaPBKyjE1r4fQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=10.0.0"
+      },
+      "peerDependencies": {
+        "bufferutil": "^4.0.1",
+        "utf-8-validate": ">=5.0.2"
+      },
+      "peerDependenciesMeta": {
+        "bufferutil": {
+          "optional": true
+        },
+        "utf-8-validate": {
+          "optional": true
+        }
+      }
     }
   }
 }