refactor(组件): 移除PostCard中的多余图标并调整MainGridLayout布局

移除PostCard组件中不再需要的右侧箭头图标，优化视觉简洁性
调整MainGridLayout中主内容区的overflow和min-width属性，解决长文本布局问题

src/components/PostCard.astro

@@ -44,7 +44,6 @@ const { remarkPluginFrontmatter } = await entry.render();
         ">
 
             {title}
-            <Icon class="text-[var(--primary)] text-[2rem] transition inline absolute translate-y-0.5 opacity-0 group-hover:opacity-100 -translate-x-1 group-hover:translate-x-0" name="material-symbols:chevron-right-rounded"></Icon>
         </a>
 
         <!-- description -->

src/layouts/MainGridLayout.astro

@@ -82,7 +82,7 @@ const mainPanelTop = siteConfig.banner.enable
 
             <SideBar class="mb-4 row-start-2 row-end-3 col-span-2 lg:row-start-1 lg:row-end-2 lg:col-span-1 lg:max-w-[17.5rem] onload-animation" headings={headings}></SideBar>
 
-            <main id="swup-container" class="transition-swup-fade col-span-2 lg:col-span-1 overflow-hidden">
+            <main id="swup-container" class="transition-swup-fade col-span-2 lg:col-span-1 overflow-visible min-w-0">
                 <div id="content-wrapper" class="onload-animation">
                     <!-- the overflow-hidden here prevent long text break the layout-->
                     <!-- make id different from windows.swup global property -->