feat: add Git card to login page dashboard

site/src/pages/index.astro

@@ -3,6 +3,7 @@ import Base from '../layouts/Base.astro';
 const activityUrl = import.meta.env.PUBLIC_ACTIVITY_URL ?? '';
 const wikiUrl     = import.meta.env.PUBLIC_WIKI_URL     ?? '';
 const plannerUrl  = import.meta.env.PUBLIC_PLANNER_URL  ?? '';
+const gitUrl      = import.meta.env.PUBLIC_GIT_URL      ?? '';
 ---
 <Base title="Bincio">
   <div id="cards" class="grid grid-cols-1 sm:grid-cols-2 gap-4 mt-4">
@@ -11,7 +12,7 @@ const plannerUrl  = import.meta.env.PUBLIC_PLANNER_URL  ?? '';
   </div>
 </Base>
 
-<script define:vars={{ activityUrl, wikiUrl, plannerUrl }}>
+<script define:vars={{ activityUrl, wikiUrl, plannerUrl, gitUrl }}>
   fetch('/api/me', { credentials: 'include' })
     .then(async r => {
       if (!r.ok) { window.location.replace('/login/'); return; }
@@ -42,6 +43,14 @@ const plannerUrl  = import.meta.env.PUBLIC_PLANNER_URL  ?? '';
           desc: 'Route planning and elevation',
           icon: '🗺️',
         },
+        {
+          key: 'git',
+          url: gitUrl,
+          show: gitUrl,
+          label: 'Git',
+          desc: 'Source code and repositories',
+          icon: '🐙',
+        },
       ].filter(s => s.show);
 
       const container = document.getElementById('cards');