fix: remove all medical device terms from user-facing text

Replace '光子美容仪' with '智美'/'智能面膜'/'我的设备' throughout.
Replace '护理' with '使用' in all UI text.
Replace '皮肤' with '检测'/'智能' where applicable.
Replace 🌸 with 💎 for brand identity.
Internal code (variable names, API paths, file names) unchanged.

miniprogram/pages/login/login.wxml

@@ -1,14 +1,14 @@
 <view class="page">
   <view class="page-header page-header-pink" style="padding-top: {{statusBarHeight + 24}}px;">
-    <view class="page-header-title">光子美容仪</view>
+    <view class="page-header-title">智美</view>
     <view class="page-header-subtitle">微信登录</view>
   </view>
 
   <view class="page-content">
-    <view class="welcome-text">欢迎使用光子美容仪</view>
+    <view class="welcome-text">欢迎使用智美</view>
 
     <view class="flower-area">
-      <text class="flower">🌸</text>
+      <text class="flower">💎</text>
       <view class="desc">登录后即可使用全部功能</view>
     </view>