Render a session's track on the map

Clicking a LiveTrack session now fetches and draws its track (line +
latest position). Garmin's own API 403s any plain server-side request
(Cloudflare bot protection), so LiveTrackClient fetches the session
page instead and pulls the track out of the server-rendered data
embedded in it. The webhook now captures the session's token too,
since the id alone isn't enough to fetch anything.

public/js/map.js

@@ -128,7 +128,7 @@ layerToggle.setActive("online");
 new GpxPanelControl(map).mount(sidebar);
 new RadarControl(map).mount(sidebar);
 new GnssControl(map).mount(sidebar);
-new LiveTrackPanelControl().mount(sidebar);
+new LiveTrackPanelControl(map).mount(sidebar);
 
 function applyStyle(name) {
   layerToggle.setActive(name);