Add loading spinner to DXCC list display

Introduces a loading spinner and message inside the dxcclist_display div to improve user feedback while HTMX loads DXPedition data and logbook checks.

application/views/workabledxcc/index.php

@@ -1,5 +1,16 @@
 <div class="container">
 
     <h2><?php echo $page_title; ?></h2>
-    <div id="dxcclist_display" hx-get="<?php echo site_url('workabledxcc/dxcclist'); ?>" hx-trigger="load"></div>
+    <div id="dxcclist_display" hx-get="<?php echo site_url('workabledxcc/dxcclist'); ?>" hx-trigger="load">
+        <!-- Loading spinner and message shown while HTMX loads content -->
+        <div class="d-flex justify-content-center align-items-center py-5">
+            <div class="text-center">
+                <div class="spinner-border text-primary mb-3" role="status" style="width: 3rem; height: 3rem;">
+                    <span class="visually-hidden">Loading...</span>
+                </div>
+                <h5 class="text-muted">Generating Table</h5>
+                <p class="text-muted">Processing DXPedition data and checking your logbook...</p>
+            </div>
+        </div>
+    </div>
 </div>