chore: improve sticker rendering and CSS specificity

Enhanced sticker rendering by adding optional chaining for safer DOM traversal and reordered sticker rendering logic to ensure proper inclusion in post content. Improved CSS specificity for sticker styling to ensure consistent application across components.

src/components/item.astro

@@ -181,6 +181,11 @@ const timeago = datetime.isBefore(dayjs().subtract(1, 'w'))
     margin-right: 2px;
   }
 
+  .content :global(.sticker) {
+    box-shadow: none;
+    border: none;
+  }
+
   .tag-box {
     flex-wrap: wrap;
   }