fix(admin/post/view): correct the thumb item index offset

修正分页图片缩略项的data-index索引偏移，使其从0开始正确对应分页下标

view/admin/post/output_view.html

@@ -301,7 +301,7 @@
         <h3>分页图片({$output.page_count} 页)</h3>
         <div class="thumb-grid">
             {volist name="pages" id="page"}
-            <div class="thumb-item" data-index="{$i}">
+            <div class="thumb-item" data-index="{$i-1}">
                 <img src="{$page.image_src|raw}" alt="第{$page.page}页">
                 <div class="thumb-bar">
                     <span class="thumb-label">第 {$page.page} 页</span>