feat(侧边栏): 添加Secbit赞助横幅到侧边栏组件

在侧边栏组件中新增Secbit赞助商的GIF横幅展示区域，位于现有赞助标下方。横幅宽度限制为280px并添加圆角样式。

src/components/widget/SideBar.astro

@@ -19,6 +19,9 @@ const className = Astro.props.class;
         <Categories class="onload-animation" style="animation-delay: 150ms"></Categories>
         <Tag class="onload-animation" style="animation-delay: 200ms"></Tag>
         <!-- 赞助标 -->
+        <div class="overflow-hidden flex justify-center">
+            <img src="/aff/secbit-banner-1.gif" alt="Secbit" class="w-full max-w-[280px] rounded-lg" />
+        </div>
         <div class="overflow-hidden flex justify-center">
             <iframe
                 src="https://support.nodeget.com/page/promotion?id=316"