feat(admin,player,api): 公共管理与优胜冠军国旗、玩家端内容对接

新增公共内容 CRUD 与批量操作；公告滚动合并管理；优胜冠军内置国家选择与单行保存；玩家端统一 usePlayerHome 对接轮播与跑马灯。

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/admin/src/router/index.ts

@@ -54,6 +54,11 @@ const router = createRouter({
           component: () => import('../views/Cashback.vue'),
           meta: { adminOnly: true },
         },
+        {
+          path: 'contents',
+          component: () => import('../views/Contents.vue'),
+          meta: { adminOnly: true },
+        },
         {
           path: 'audit',
           component: () => import('../views/Audit.vue'),