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/ai-recommend/ai-recommend.json

@@ -1,6 +1,7 @@
 {
   "usingComponents": {
     "navigation-bar": "/components/navigation-bar/navigation-bar",
+    "cached-image": "/components/cached-image/cached-image",
     "empty-state": "/components/empty-state/empty-state",
     "v2-overlay": "/components/v2-overlay/index"
   }

miniprogram/pages/ai-recommend/ai-recommend.wxml

@@ -44,7 +44,7 @@ module.exports = { cls: cls }
     <view class="ai-cover">
       <view class="collage {{cl.cls(clothes.length)}}">
         <view class="cg" wx:for="{{clothes}}" wx:key="clothes_uuid" wx:if="{{index < 4}}">
-          <image wx:if="{{item.processed_image}}" class="pic" src="{{item.processed_image}}" mode="aspectFill" />
+          <cached-image wx:if="{{item.processed_image}}" class="pic" src="{{item.processed_image}}" mode="aspectFill" />
           <view wx:else class="ph icon icon-hanger"></view>
         </view>
         <view wx:if="{{clothes.length > 4}}" class="cg-more">+{{clothes.length - 4}}</view>
@@ -77,7 +77,7 @@ module.exports = { cls: cls }
         <view class="ai-items-row">
           <view class="ai-chip" wx:for="{{clothes}}" wx:key="clothes_uuid">
             <view class="ai-thumb">
-              <image wx:if="{{item.processed_image}}" class="pic" src="{{item.processed_image}}" mode="aspectFill" />
+              <cached-image wx:if="{{item.processed_image}}" class="pic" src="{{item.processed_image}}" mode="aspectFill" />
               <view wx:else class="ph icon icon-hanger"></view>
             </view>
             <text class="ai-chip-n">{{item.name || '未命名'}}</text>