Initial commit: private Texas Hold'em ring game site (lobby + table stub)

- 6-digit access key gate with long-lived HttpOnly cookie, brute-force limits
- Lobby with saved player name and live table list
- Table creation (name, starting stack, blinds, blind timer)
- Table play screen stub (seats, button/SB/BB, phase, blinds, timer)
- Security hardening: strict CSP, origin checks, host pinning, input sanitizing

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

package.json

@@ -0,0 +1,18 @@
+{
+  "name": "friends-holdem",
+  "version": "0.1.0",
+  "private": true,
+  "description": "友達用テキサスホールデム リングゲーム",
+  "main": "server/index.js",
+  "scripts": {
+    "start": "node server/index.js",
+    "dev": "node --watch server/index.js"
+  },
+  "engines": {
+    "node": ">=18"
+  },
+  "dependencies": {
+    "express": "^4.22.3",
+    "socket.io": "^4.8.4"
+  }
+}