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/src/pages/admin/studio.vue

@@ -0,0 +1,15 @@
+<template>
+  <view class="page">
+    <view class="placeholder">
+      <text>工作室设置 - 待实现</text>
+    </view>
+  </view>
+</template>
+
+<script setup lang="ts">
+</script>
+
+<style lang="scss" scoped>
+.page { min-height: 100vh; background: #f5f5f5; }
+.placeholder { display: flex; align-items: center; justify-content: center; height: 400rpx; color: #999; }
+</style>