Add geolocate control to the map

Lets the user center the map on their current location, with an
accuracy circle and continuous tracking.

public/js/map.js

@@ -1,6 +1,7 @@
 import {
   Map as MaplibreMap,
   NavigationControl,
+  GeolocateControl,
   addProtocol,
 } from "/vendor/maplibre-gl/maplibre-gl.mjs";
 import { RadarControl } from "/js/radar.js";
@@ -70,6 +71,14 @@ const map = new MaplibreMap({
 });
 
 map.addControl(new NavigationControl(), "top-right");
+map.addControl(
+  new GeolocateControl({
+    positionOptions: { enableHighAccuracy: true },
+    trackUserLocation: true,
+    showAccuracyCircle: true,
+  }),
+  "top-right",
+);
 map.addControl(new RadarControl(map), "top-right");
 
 const layerToggle = new LayerToggleControl(applyStyle);