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/utils/auth.ts

@@ -0,0 +1,44 @@
+import { post } from './request'
+import type { UserProfileResponse } from '@mp-pilates/shared'
+
+interface LoginResponse {
+  readonly token: string
+  readonly user: UserProfileResponse
+}
+
+export async function wxLogin(): Promise<LoginResponse> {
+  return new Promise((resolve, reject) => {
+    uni.login({
+      provider: 'weixin',
+      success: async (loginRes) => {
+        try {
+          const result = await post<LoginResponse>('/auth/login', {
+            code: loginRes.code,
+          })
+          uni.setStorageSync('token', result.token)
+          resolve(result)
+        } catch (err) {
+          reject(err)
+        }
+      },
+      fail: (err) => {
+        reject(new Error(err.errMsg || '微信登录失败'))
+      },
+    })
+  })
+}
+
+export async function wxBindPhone(e: {
+  readonly detail: { readonly encryptedData: string; readonly iv: string }
+}): Promise<UserProfileResponse> {
+  const { encryptedData, iv } = e.detail
+  return post<UserProfileResponse>('/auth/phone', { encryptedData, iv })
+}
+
+export function isLoggedIn(): boolean {
+  return !!uni.getStorageSync('token')
+}
+
+export function logout(): void {
+  uni.removeStorageSync('token')
+}