fix: resolve Leaflet window.L not being set in esbuild bundle

The esbuild bundle wraps everything in a 'use strict' IIFE, causing the
leaflet UMD module to take the CommonJS path instead of setting
window.leaflet. The entry point check window.leaflet && !window.L always
failed, so window.L was never assigned and the map never initialized.

- Add leaflet-global.js to import leaflet-minimal and set window.L before
  plugins execute (ESM source-order evaluation guarantees this)
- Replace the broken window.leaflet check in map-bundle-entry.js with an
  import of leaflet-global.js

assets/js/leaflet-global.js

@@ -0,0 +1,7 @@
+// Sets window.L from the imported leaflet module.
+// Required because esbuild bundles everything in a "use strict" IIFE,
+// causing the leaflet UMD to take the CommonJS path instead of setting
+// window.leaflet. Plugins and hooks expect window.L to exist.
+import * as leafletModule from "../vendor/js/leaflet-minimal.js";
+
+window.L = leafletModule;

assets/js/map-bundle-entry.js

@@ -1,11 +1,9 @@
-// Map bundle entry point - combines Leaflet and map plugins
-import "../vendor/js/leaflet-minimal.js";
+// Map bundle entry point — combines Leaflet and map plugins.
+//
+// ESM evaluates side-effect imports in source order, so leaflet-global.js
+// runs (and sets window.L) before plugins-optimized.js, which references L.
+import "./leaflet-global.js";
 import "../vendor/js/plugins-optimized.js";
 
-// Ensure Leaflet is available as window.L (standard convention)
-if (window.leaflet && !window.L) {
-  window.L = window.leaflet;
-}
-
 // Mark bundle as loaded
-window.mapBundleLoaded = true;
+window.mapBundleLoaded = true;