chore: 移除 playground 目录及相关配置

清理不再需要的 playground 项目，包括：
- 删除 playground 源码目录及所有相关文件
- 从 pnpm-workspace.yaml 移除 playground 工作区
- 从 .vscode 配置中移除 playground 相关路径
- 从 package.json 脚本中移除 build:play 和 dev:play 命令
- 从 vben-admin.code-workspace 移除 playground 项目引用
- 从 .vscode/launch.json 移除 playground 调试配置

.vscode/launch.json

@@ -2,15 +2,6 @@
   "$schema": "https://json.schemastore.org/launchsettings.json",
   "version": "0.2.0",
   "configurations": [
-    {
-      "type": "chrome",
-      "name": "vben admin playground dev",
-      "request": "launch",
-      "url": "http://localhost:5555",
-      "env": { "NODE_ENV": "development" },
-      "sourceMaps": true,
-      "webRoot": "${workspaceFolder}/playground"
-    },
     {
       "type": "chrome",
       "name": "vben admin antd dev",

.vscode/settings.json

@@ -199,7 +199,6 @@
 
   "i18n-ally.localesPaths": [
     "packages/locales/src/langs",
-    "playground/src/locales/langs",
     "apps/*/src/locales/langs"
   ],
   "i18n-ally.pathMatcher": "{locale}/{namespace}.{ext}",