Add navigation to detail

src/pictures/static/pictures/list.css

@@ -20,3 +20,7 @@
     flex-grow: 1;
     margin-left: 1em;
 }
+
+.message {
+    cursor: pointer;
+}

src/pictures/templates/pictures/messages-list.html

@@ -7,7 +7,7 @@
 
 {% block content %}
     {% for message in messages %}
-        <div class="message">
+        <div class="message" onclick="window.location.href = '/{{ message.id }}/';">
             <div class="picture-preview">
                 {% if message.media_files.first %}
                     <img src="{{ message.media_files.first.file.url }}" alt="Photo">