Refactor site templates to include footer partial and update page paths

- Added a footer partial to improve code reusability across templates.
- Updated paths for the 'about' and 'badges' pages to 'om-oss.html' and 'om-markning.html', respectively.
- Removed redundant footer code from individual templates, replacing it with a dynamic footer inclusion.

templates/single.html

@@ -21,15 +21,6 @@
     </div>
   </main>
 
-  <footer class="site-footer">
-    <div class="container">
-      <p>Ursprung Sverige &copy; {{ year }}</p>
-      <p class="footer-tagline">Stöd svensk ekonomi och kultur</p>
-      <nav class="footer-nav">
-        <a href="../om-oss.html">Om oss</a>
-        <a href="../om-markning.html">Om märkning</a>
-      </nav>
-    </div>
-  </footer>
+{{ footer }}
 </body>
 </html>