Implement PWA features: add service worker, manifest, and offline page; enhance footer and header navigation

_includes/footer.html

@@ -1,11 +1,21 @@
 <footer class="cyber-razor-top bg-black">
-  {% if site.footer_links and site.footer_links.size > 0 %}
-    {% for link in site.footer_links %}
-      <a href="{{ link.url }}" class="cyber-a">{{ link.title }}</a>
+  <ul class="tabs mobile-tabs">
+    <li class="tab col s1 {% if page.url == "/" %}bg-red{% else %}bg-dark{% endif %}"><a href="{{ "/" | relative_url }}" class="cyber-a"><i class="material-icons">home</i></a></li>
+    {% for tab in sorted_pages %}
+      {% if tab.title and tab.permalink and tab.nav != false %}
+        <li class="tab col s1 {% if page.url == tab.url %}bg-red{% else %}bg-dark{% endif %}">
+          <a href="{{ tab.url | relative_url }}" target="_self" class="cyber-a">
+            {% if tab.icon %}
+              <i class="material-icons">{{ tab.icon }}</i>
+            {% else %}
+              {{ tab.title }}
+            {% endif %}
+          </a>
+        </li>
+      {% endif %}
     {% endfor %}
-  {% else %}
-    <span></span> <!-- Erzeugt leeren, aber sichtbaren Footer -->
-  {% endif %}
+  </ul>
+  <span></span>
 </footer>
 <script
 			  src="https://code.jquery.com/jquery-3.7.1.min.js"