backend: include links to tags in media#show

templates/media.html.ep

@@ -14,7 +14,11 @@
   <dt>Content-Type</dt>
   <dd><%= $media->{content_type} %></dd>
   <dt>Tags</dt>
-<% for my $tag ($media->{tags}->@*) { %>
-  <dd><%= link_to $tag => url_for("tag_show", tag_id_or_name => $tag) %></dd>
-<% } %>
+% if ($media->{tags}->@* == 0) {
+  <dd>None yet.</dd>
+% } else {
+  <dd><%= c($media->{tags}->@*)
+    ->map(sub { link_to $_ => url_for("tag_show", tag_id_or_name => $_) })
+    ->join(", ") %>.</dd>
+% }
 </dl>