refactor: split project into web and server directories

- Move frontend to web/ directory
- Add server/ directory for backend
- Restructure project for前后端分离架构

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/src/main.js

@@ -0,0 +1,21 @@
+import { createApp } from 'vue'
+import { MotionPlugin } from '@vueuse/motion'
+import PrimeVue from 'primevue/config'
+import Aura from '@primevue/themes/aura'
+import 'primeicons/primeicons.css'
+import App from './App.vue'
+
+const app = createApp(App)
+
+app.use(MotionPlugin)
+app.use(PrimeVue, {
+  theme: {
+    preset: Aura,
+    options: {
+      darkModeSelector: '.dark',
+      cssLayer: false
+    }
+  }
+})
+
+app.mount('#app')