fix: higher-res boundaries (50m), hide city names, country-only labels

- 50m GeoJSON for cleaner country outlines (was 110m)
- Hide all symbol layers except country/continent names
- Country names only visible at zoom >= 3

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

layouts/shortcodes/world-map.html

@@ -79,7 +79,7 @@ function ifkInitMap() {
       }
     });
 
-    fetch('{{ "data/countries-110m.json" | relURL }}')
+    fetch('{{ "data/countries-50m.json" | relURL }}')
       .then(function(r) { return r.json(); })
       .then(function(topo) {
         var geo = topojson.feature(topo, topo.objects.countries);
@@ -124,11 +124,14 @@ function ifkInitMap() {
           }
         }, firstLabel);
 
-        // Hide country labels below zoom 3
+        // Hide all labels except country names at zoom >= 3
         layers.forEach(function(l) {
-          if (l.type === 'symbol' && (l.id.indexOf('country') >= 0 || l.id.indexOf('place') >= 0 || l.id.indexOf('continent') >= 0)) {
-            window._ifkMap.setLayoutProperty(l.id, 'visibility', 'visible');
-            window._ifkMap.setLayerZoomRange(l.id, 3, 24);
+          if (l.type === 'symbol') {
+            if (l.id.indexOf('country') >= 0 || l.id.indexOf('continent') >= 0) {
+              window._ifkMap.setLayerZoomRange(l.id, 3, 24);
+            } else {
+              window._ifkMap.setLayoutProperty(l.id, 'visibility', 'none');
+            }
           }
         });