fix(admin): render Leaflet maps in template preview

The .card wrapper has overflow:hidden which clips Leaflet's
absolutely-positioned tile layers. Override to overflow:visible
on the rendered-article card. Add .catch() to map fetch calls.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/padelnomics/admin/templates/admin/template_preview.html

@@ -25,8 +25,8 @@
     </div>
   </div>
 
-  {# Rendered article #}
-  <div class="card">
+  {# Rendered article — overflow:visible needed so Leaflet tile layers render #}
+  <div class="card" style="overflow: visible;">
     <h2 class="text-lg mb-4">Rendered HTML</h2>
     <div class="article-body" style="max-width: none;">
       {{ preview.html | safe }}

web/src/padelnomics/static/js/article-maps.js

@@ -58,7 +58,8 @@
           bounds.push([c.lat, c.lon]);
         });
         if (bounds.length) map.fitBounds(bounds, { padding: [24, 24] });
-      });
+      })
+      .catch(function(err) { console.error('Country map fetch failed:', err); });
   }
 
   var VENUE_ICON = L.divIcon({
@@ -94,7 +95,8 @@
             .bindTooltip(tip, { className: 'map-tooltip', direction: 'top', offset: [0, -7] })
             .addTo(map);
         });
-      });
+      })
+      .catch(function(err) { console.error('City map fetch failed:', err); });
   }
 
   /* Dynamically load Leaflet JS then init maps */