refactor: 优化前端布局结构并移除管理页面链接

src/app.css

@@ -34,7 +34,17 @@ body {
   font-family: var(--font-sans);
   background-color: var(--bg-color);
   color: var(--text-color);
-  line-height: 1.8;
+	line-height: 1.8;
+}
+
+.frontend-layout {
+  display: flex;
+  flex-direction: column;
+  min-height: 100vh;
+}
+
+.frontend-layout > main {
+  flex: 1 0 auto;
 }
 
 h1, h2, h3, h4, h5, h6 {

src/routes/+layout.svelte

@@ -34,6 +34,7 @@
 {#if $page.url.pathname.startsWith('/admin')}
 	{@render children()}
 {:else}
+<div class="frontend-layout">
 	<header class="header {scrolled ? 'scrolled' : ''}">
 		<div class="container wide">
 			<a href="/" class="brand">{$page.data.site?.title || 'BlogFlare'}</a>
@@ -41,7 +42,6 @@
 				<a href="/" class={$page.url.pathname === '/' ? 'active' : ''}>首页</a>
 				<a href="/archive" class={$page.url.pathname.startsWith('/posts') || $page.url.pathname.startsWith('/archive') ? 'active' : ''}>{$page.data.aliases?.post || '文章'}</a>
 				<a href="/about" class={$page.url.pathname.startsWith('/about') ? 'active' : ''}>关于</a>
-				<a href="/admin" class={$page.url.pathname.startsWith('/admin') ? 'active' : ''}>后台</a>
 			</nav>
 		</div>
 	</header>
@@ -83,4 +83,5 @@
 			</a>
 		</div>
 	</aside>
+</div>
 {/if}