Maps raw cloud cover to six distinct stepped colour bands (clear green
through overcast red) on a dark navy background, with fine gradation
below 30% where conditions matter for astrophotography and two coarse
bands above. Skips OSM base map and alpha blending entirely.
The triangulation now stores raw cover values; scale_cloud_cover() is
applied post-blur only in the default blending mode, keeping its
behaviour identical.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
