Add AdSense script to client page

src/client/index.html

@@ -1,6 +1,8 @@
 <!doctype html>
 <html lang="ko">
-<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover"><meta name="theme-color" content="#ffffff"><title>쎄쎄쎄:기공대전</title></head>
+<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover"><meta name="theme-color" content="#ffffff"><title>쎄쎄쎄:기공대전</title>
+  <script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-3181563320128730" crossorigin="anonymous"></script>
+</head>
 <body class="player-app" data-screen="home">
   <span id="online-count" class="online-count" role="status">접속 확인 중</span>
   <div class="app">