feat: 品牌更名为 51短剧,替换新 logo

- 页面标题、登录、首页、header 文案改为「51短剧后台管理系统」
- public/icon.webp 与 src/assets/images/icon.webp 替换为新 logo
- prod_build.sh 部署路径同步改为 /server/51dj/webadmin/

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

public/index.html

@@ -6,7 +6,7 @@
   <meta http-equiv="X-UA-Compatible" content="IE=edge" />
   <meta name="viewport" content="width=device-width,initial-scale=1.0" />
   <link rel="icon" type="image/webp" href="<%= BASE_URL %>icon.webp" />
-  <title>黄果漫剧后台管理系统</title>
+  <title>51短剧后台管理系统</title>
 </head>
 
 <body>