New mastodon post feature

templates/index.html

@@ -3,6 +3,7 @@
 {% block content %}
   <section class="intro">
     <p>Choose a recent Immich photo to request Mastodon-friendly alt text.</p>
+    <p><a class="button-link" href="{{ url_for('main.compose_select') }}">Compose a Mastodon post</a></p>
   </section>
 
   {% if error_message %}