Speed up Wereldexport map loading dramatically.

Limit world overview payload, optimize SQL joins, cache bundle and tiles, reuse map instance, and show loading state.

cockpit/static/js/export-intel-map.js

@@ -170,6 +170,10 @@ window.ExportIntelMap = (function () {
   function init(containerId) {
     var el = document.getElementById(containerId);
     if (!el || !window.L) return null;
+    if (map && map.getContainer() === el) {
+      invalidateMapSize();
+      return map;
+    }
     if (map) {
       map.remove();
       map = null;