feat(ui): Repeat xd-client UI with modern adaptive features

- Integrated Tailwind CSS v4 and Shadcn UI components from xd-client
- Adopted xd-client modern aesthetic (oklch, radial gradients, glassmorphism)
- Combined with modern adaptive 3-tier navigation logic
- Refactored all pages (Profile, Login, Settings, Messages, Schedule, Grades, Debts)
- Enhanced ThemeProvider with dynamic Material You palette generation
- Polished overall UX and animations

Refs #3
Co-Authored-By: Claude <noreply@anthropic.com>

vite.config.ts

@@ -1,7 +1,20 @@
-import { defineConfig } from 'vite'
-import react from '@vitejs/plugin-react'
+import { defineConfig } from 'vite';
+import react from '@vitejs/plugin-react';
+import tailwindcss from '@tailwindcss/postcss';
+import autoprefixer from 'autoprefixer';
+import path from 'path';
 
-// https://vite.dev/config/
+// https://vitejs.dev/config/
 export default defineConfig({
   plugins: [react()],
-})
+  resolve: {
+    alias: {
+      '@': path.resolve(__dirname, './src'),
+    },
+  },
+  css: {
+    postcss: {
+      plugins: [tailwindcss(), autoprefixer()],
+    },
+  },
+});