The cluster source, its layers, the expansion zoom and the DOM bubbles
now live in placeClusterLayers.ts with their own tests, which brings
MapViewGL back under its size baseline instead of growing it. Lowers the
size and eslint baselines that this change made smaller.
The MapLibre and Mapbox maps painted their place clusters as a canvas
circle plus a symbol layer, so the count used whatever glyphs the map
style ships and the bubble had no hover. They are now DOM pins built by
the same markup and CSS as the Leaflet bubbles, with the same sizes,
font and hover scale. The canvas layers stay, invisible, as the hit
area the track and route layers check a click against.
Maurice