feat: 添加完整的前端管理系统 (VbenAdmin)

- 添加基于 VbenAdmin + Vue3 + Element Plus 的前端管理系统
- 包含完整的 UI 组件库和工具链
- 支持多应用架构 (web-ele, backend-mock, playground)
- 包含完整的开发规范和配置
- 修复 admin 目录的子模块问题，确保正确提交

admin/packages/effects/layouts/src/widgets/preferences/preferences.vue

@@ -0,0 +1,72 @@
+<script lang="ts" setup>
+import { computed } from 'vue';
+
+import { Settings } from '@vben/icons';
+import { $t, loadLocaleMessages } from '@vben/locales';
+import { preferences, updatePreferences } from '@vben/preferences';
+import { capitalizeFirstLetter } from '@vben/utils';
+
+import { useVbenDrawer } from '@vben-core/popup-ui';
+import { VbenButton } from '@vben-core/shadcn-ui';
+
+import PreferencesDrawer from './preferences-drawer.vue';
+
+const [Drawer, drawerApi] = useVbenDrawer({
+  connectedComponent: PreferencesDrawer,
+});
+
+/**
+ * preferences 转成 vue props
+ * preferences.widget.fullscreen=>widgetFullscreen
+ */
+const attrs = computed(() => {
+  const result: Record<string, any> = {};
+  for (const [key, value] of Object.entries(preferences)) {
+    for (const [subKey, subValue] of Object.entries(value)) {
+      result[`${key}${capitalizeFirstLetter(subKey)}`] = subValue;
+    }
+  }
+  return result;
+});
+
+/**
+ * preferences 转成 vue listener
+ * preferences.widget.fullscreen=>@update:widgetFullscreen
+ */
+const listen = computed(() => {
+  const result: Record<string, any> = {};
+  for (const [key, value] of Object.entries(preferences)) {
+    if (typeof value === 'object') {
+      for (const subKey of Object.keys(value)) {
+        result[`update:${key}${capitalizeFirstLetter(subKey)}`] = (
+          val: any,
+        ) => {
+          updatePreferences({ [key]: { [subKey]: val } });
+          if (key === 'app' && subKey === 'locale') {
+            loadLocaleMessages(val);
+          }
+        };
+      }
+    } else {
+      result[key] = value;
+    }
+  }
+  return result;
+});
+</script>
+<template>
+  <div>
+    <Drawer v-bind="{ ...$attrs, ...attrs }" v-on="listen" />
+
+    <div @click="() => drawerApi.open()">
+      <slot>
+        <VbenButton
+          :title="$t('preferences.title')"
+          class="bg-primary flex-col-center size-10 cursor-pointer rounded-l-lg rounded-r-none border-none"
+        >
+          <Settings class="size-5" />
+        </VbenButton>
+      </slot>
+    </div>
+  </div>
+</template>