feat(image-cache): 新增图片本地缓存并全站接入

引入 cached-image 组件与 image-cache 工具，实现签名 URL 稳定 key 剥离、downloadFile 落盘及 TTL/LRU 清理，替换 11 个页面与 clothes-card 共 22 处网络图片渲染点，减少 CDN 重复流量。

miniprogram/pages/profile/profile.wxml

@@ -27,7 +27,7 @@
     <!-- 资料区：大号头像 + 衬线昵称 + 胶囊标签 -->
     <view wx:else class="pf-hero">
       <view class="pf-av">
-        <image wx:if="{{userInfo.avatar}}" class="pf-av-img" src="{{userInfo.avatar}}" mode="aspectFill" />
+        <cached-image wx:if="{{userInfo.avatar}}" class="pf-av-img" src="{{userInfo.avatar}}" mode="aspectFill" />
         <view wx:else class="icon icon-user"></view>
       </view>
       <view class="pf-info">
@@ -150,7 +150,7 @@
 
       <view class="sheet-body">
         <view class="avatar-wrap">
-          <image wx:if="{{editForm.avatar}}" class="avatar-img" src="{{editForm.avatar}}" mode="aspectFill" />
+          <cached-image wx:if="{{editForm.avatar}}" class="avatar-img" src="{{editForm.avatar}}" mode="aspectFill" />
           <view wx:else class="icon icon-user avatar-placeholder"></view>
           <button class="avatar-btn" open-type="chooseAvatar" bindchooseavatar="onChooseAvatar"></button>
         </view>