Adjust layers at low zoom

Some related problems:

at low zooms, trip generator layers based on polygons (the first 3) are not really visible
at low zooms, point layers like cycle parking and traffic counts (and soon stats19) appear to just sample points. It's unclear where to zoom to see more detail
Use of color + circles/polygons to represent many of these layers isn't ideal. Symbols/icons could be much nicer.
at low zooms, some objects have tooltips and are clickable, but this feels inappropriate -- it's practically impossible to tell what object is being hovered on when it's so tiny

Possible solutions (not mutually exclusive):

https://maplibre.org/maplibre-gl-js/docs/examples/cluster/ for points. From quickly trying this out, this only works on GeoJSON sources, not vector tiles like pmtiles. So only OK if we can afford to load the whole geojson file at once.
https://maplibre.org/maplibre-gl-js/docs/examples/heatmap-layer/ for points. This does seem to work with pmtiles.
Adding -zg to tippecanoe makes more/all points show up at low zooms. If the size per tile gets too big, we could maybe consider dropping some attributes at low zooms -- especially if we decide we don't need hovering/clicking at that level. https://github.com/felt/tippecanoe has lots of docs/examples.
Use maplibre symbol layers

acteng / atip