feat: switch to Stadia Alidade Smooth Dark map tiles

themes/intotheeast/templates/map.html.twig

@@ -43,8 +43,10 @@ var ENTRIES = {{ map_entries|json_encode|raw }};
 
 var map = L.map('trip-map', { minZoom: 2, maxZoom: 18 });
 
-L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
-    attribution: '© <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
+// TODO: add Stadia API key before launch — free dev use requires no key, production does
+L.tileLayer('https://tiles.stadiamaps.com/tiles/alidade_smooth_dark/{z}/{x}/{y}{r}.png', {
+    maxZoom: 20,
+    attribution: '© <a href="https://stadiamaps.com/">Stadia Maps</a> © <a href="https://openmaptiles.org/">OpenMapTiles</a> © <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
 }).addTo(map);
 
 // GPX route tracks