build: add map.js bundle — MapLibre GL, toGeoJSON, MapUtils

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Vgmzx8VTTTmCskSpQtsLTr

themes/intotheeast/js/src/map.js

@@ -1 +1,9 @@
-// placeholder — replaced in Task 4
+import maplibregl from 'maplibre-gl';
+import 'maplibre-gl/dist/maplibre-gl.css';
+import toGeoJSON from '@mapbox/togeojson';
+
+/* maplibre-utils.js attaches MapUtils to window as a side effect */
+import '../maplibre-utils.js';
+
+window.maplibregl = maplibregl;
+window.toGeoJSON  = toGeoJSON;