[FEAT] Enhance route&neighbours contrast over map

[gztproject]

Is your feature request related to a problem? Please describe.
Route and neighbour overlays are rendered in pink, which is great for dark maps, but poorly visible over OSM and OpenTopo maps.

Describe the solution you'd like
A light and dark color schemes that can be toggled manually or selected automatically based on lightness/darkness of the map tiles.
Maybe even a colour + transparency picker in settings to set the light and dark scheme. Instead of full/dashed line to distinguish between routes and neighbours, use different colours.

I realize there's a theme editor but a light/dark set based on map selection might still come in handy.