Link the source code on GitHub from the footer

The site now lives in a public repo; point readers at it in all three
languages. Both pages had the same footer, so it becomes one partial
(absorbing the credits partial).

Assisted-by: Claude:opus-5

views/_credits.erb

@@ -1,2 +0,0 @@
-<p class="credits"><%= t(:credits_ai) %>
-  <%== format(Rack::Utils.escape_html(t(:credits_hym)), link: '<a href="https://hackyourmom.com/en/karta-data-czentriv-na-rasii/" target="_blank" rel="noopener">hackyourmom</a>') %></p>

views/_footer.erb

@@ -0,0 +1,6 @@
+<footer>
+  <p><%= t(:footer) %></p>
+  <p class="credits"><%= t(:credits_ai) %>
+    <%== format(Rack::Utils.escape_html(t(:credits_hym)), link: '<a href="https://hackyourmom.com/en/karta-data-czentriv-na-rasii/" target="_blank" rel="noopener">hackyourmom</a>') %></p>
+  <p>© <%= Date.today.year %> <a href="https://asxp.io">asxp.io</a> · <a href="<%= BingoWeb::SOURCE_URL %>" rel="noopener"><%= t(:source_code) %></a></p>
+</footer>

views/dc.erb

@@ -27,9 +27,5 @@
   </nav>
   <p><a href="/<%= @locale %>"><%= t(:back) %></a></p>
 
-  <footer>
-    <p><%= t(:footer) %></p>
-    <%== erb :_credits, layout: false %>
-    <p>© <%= Date.today.year %> <a href="https://asxp.io">asxp.io</a></p>
-  </footer>
+  <%== erb :_footer, layout: false %>
 </main>

views/index.erb

@@ -84,11 +84,7 @@
     </ul>
   </section>
 
-  <footer>
-    <p><%= t(:footer) %></p>
-    <%== erb :_credits, layout: false %>
-    <p>© <%= Date.today.year %> <a href="https://asxp.io">asxp.io</a></p>
-  </footer>
+  <%== erb :_footer, layout: false %>
 </main>
 
 <% b.cells.each do |dc| %>