feat: add github entry

src/components/BaseHeader.astro

@@ -1,6 +1,7 @@
 ---
 import {metadata} from "../consts";
 import ThemeIcon from './ThemeIcon.astro'
+import GitHubIcon from '@/assets/icon/github.svg?url'
 ---
 
 <header>
@@ -13,7 +14,9 @@ import ThemeIcon from './ThemeIcon.astro'
       <ul class="menu">
         <li class="menu-item"><a href="/">首页</a></li>
         <li class="menu-item"><a href="/archive">归档</a></li>
-        <!--<li class="menu-item"><a href="/">分类</a></li>-->
+        <li class="menu-item"><a target="_blank" href="https://git.ua42.com">
+          <img class="github-icon" src={GitHubIcon} alt="GitHub"/>
+        </a></li>
         <!--<li class="menu-item"><a href="/">关于</a></li>-->
       </ul>
 
@@ -72,7 +75,15 @@ import ThemeIcon from './ThemeIcon.astro'
   }
 
   .menu-item {
-    text-align: center;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+  }
+
+  .github-icon {
+    width: 18px;
+    height: 18px;
+    display: block;
   }
 
   .main-nav .menu-item a {
@@ -95,4 +106,8 @@ import ThemeIcon from './ThemeIcon.astro'
   :global(.dark) .main-nav .menu-item a:hover {
     color: rgba(255, 255, 255, .8);
   }
+
+  :global(.dark) .github-icon {
+    filter: invert(1);
+  }
 </style>