feat(app): initialize uni-app with routing, stores, and infrastructure

- Vue 3 + TypeScript + Pinia + SCSS
- 3-tab navigation (home, booking, profile) + 11 sub-pages
- HTTP client with JWT auth, request interceptors
- Pinia stores: user (auth, profile, memberships), studio, booking
- Utility functions: price formatting, date helpers
- WeChat login helper
- All pages as stubs ready for implementation

packages/app/vite.config.ts

@@ -0,0 +1,12 @@
+import { defineConfig } from 'vite'
+import uni from '@dcloudio/vite-plugin-uni'
+import { resolve } from 'path'
+
+export default defineConfig({
+  plugins: [uni()],
+  resolve: {
+    alias: {
+      '@': resolve(__dirname, 'src'),
+    },
+  },
+})