Multiplayer mode: server, room tokens, docker setup, and client UI

server/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "ttt-server",
+  "private": true,
+  "type": "commonjs",
+  "scripts": { "start": "node server.js" },
+  "dependencies": {
+    "express": "^5.2.1",
+    "ws": "^8.21.3",
+    "sql.js": "^1.14.2"
+  }
+}