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/outfit/outfit.wxml

@@ -68,7 +68,7 @@
       <view class="of-card" bindtap="onGuestOutfitTap">
         <view class="collage collage--2">
           <view class="cg" wx:for="{{guestOutfit.items}}" wx:key="clothes_uuid">
-            <image class="pic" src="{{item.processed_image}}" mode="aspectFit" />
+            <cached-image class="pic" src="{{item.processed_image}}" mode="aspectFit" />
           </view>
         </view>
         <view class="of-trow">
@@ -98,7 +98,7 @@
       >
         <!-- 作者行：仅社区分段 -->
         <view class="of-author" wx:if="{{activeTab === 2}}">
-          <image wx:if="{{item.owner_avatar}}" class="of-av" src="{{item.owner_avatar}}" mode="aspectFill" />
+          <cached-image wx:if="{{item.owner_avatar}}" class="of-av" src="{{item.owner_avatar}}" mode="aspectFill" />
           <view wx:else class="of-av">
             <view class="icon icon-user"></view>
           </view>
@@ -109,7 +109,7 @@
         <!-- 无缝拼图封面（_covers 由 outfitCover 组装，缺失时整体不渲染，避免 1:1 空白方块撑满屏幕） -->
         <view wx:if="{{item._covers}}" 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>
@@ -172,7 +172,7 @@
         <view class="gd-items">
           <view class="gd-item" wx:for="{{guestOutfit.items}}" wx:key="clothes_uuid">
             <view class="gd-item-img">
-              <image class="pic" src="{{item.processed_image}}" mode="aspectFit" />
+              <cached-image class="pic" src="{{item.processed_image}}" mode="aspectFit" />
             </view>
             <view class="tile-name">{{item.name}}</view>
             <view class="tile-sub">{{item.category_main}}{{item.category_sub ? ' · ' + item.category_sub : ''}}</view>