Marker (pin) labels previously inherited the app's default text color,
which reads white and disappears on light basemaps. Set each label's
text color in applyFrame() against the active style: black by default
(light basemaps osm-bright/positron/toner) and white only on the one
dark basemap (dark-matter). Re-evaluated every frame so a style switch
re-colors visible labels on the next applied frame.
Add a contract test pinning the dark-basemap detection and the
black-by-default / white-on-dark ternary.
Pike
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