perf: 优化前端加载速度

- 改用 mime 标准库替代硬编码 MIME 类型（更优雅）
- 全局 gzip 中间件替代手动压缩（覆盖所有响应）
- ECharts 改为动态 import，首屏不再加载 1.1MB
- manualChunks 拆分 vue-vendor/ui-vendor 减小主包
- 首屏 gzip 体积从 544KB 降至 236KB（减少 57%）

frontend/src/pages/admin/index.vue

@@ -1,6 +1,5 @@
 <script setup lang="ts">
 import { ArrowRight, DollarSign, Key, LayoutGrid, Loader2, Ticket, Users } from 'lucide-vue-next'
-import * as echarts from 'echarts'
 import { useColorMode } from '@vueuse/core'
 import { computed, nextTick, onMounted, onUnmounted, ref, watch } from 'vue'
 import { useI18n } from 'vue-i18n'
@@ -237,7 +236,10 @@ async function initMapChart() {
     return
 
   try {
-    const worldResponse = await fetch('/world.json')
+    const [{ default: echarts }, worldResponse] = await Promise.all([
+      import('echarts'),
+      fetch('/world.json'),
+    ])
 
     if (!worldResponse.ok) {
       throw new Error('Failed to load world map data')

frontend/vite.config.ts

@@ -112,6 +112,10 @@ export default defineConfig({
         },
         entryFileNames: 'assets/[name]-[hash].js',
         assetFileNames: 'assets/[name]-[hash].[ext]',
+        manualChunks: {
+          'vue-vendor': ['vue', 'vue-router', 'vue-i18n', 'pinia', '@vueuse/core'],
+          'ui-vendor': ['reka-ui', 'class-variance-authority', 'clsx', 'tailwind-merge', 'lucide-vue-next'],
+        },
       },
     },
   },