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-pending/ai-pending.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-pending/ai-pending.wxml

@@ -63,7 +63,7 @@
         <!-- 无缝拼图封面 -->
         <view class="collage {{item._collageCls}}">
           <view class="cg" wx:for="{{item._covers}}" wx:for-item="c" wx:key="k">
-            <image wx:if="{{c.img}}" class="pic" src="{{c.img}}" mode="aspectFill" lazy-load />
+            <cached-image wx:if="{{c.img}}" class="pic" src="{{c.img}}" mode="aspectFill" lazy-load="{{true}}" />
             <view wx:else class="ph icon icon-hanger"></view>
           </view>
           <view wx:if="{{item._moreCount > 0}}" class="cg-more">+{{item._moreCount}}</view>