refactor: migrate demo applications to playground (#4116)

* chore: detail adjustment

* refactor: Migrate demo applications to playground

* perf: logic optimization

* chore: update docs

* chore: update docs

playground/src/preferences.ts

@@ -0,0 +1,12 @@
+import { defineOverridesPreferences } from '@vben/preferences';
+
+/**
+ * @description 项目配置文件
+ * 只需要覆盖项目中的一部分配置，不需要的配置不用覆盖，会自动使用默认配置
+ */
+export const overridesPreferences = defineOverridesPreferences({
+  // overrides
+  app: {
+    name: import.meta.env.VITE_APP_TITLE,
+  },
+});