Function validateScales

Validates the scale constraints of a style — scaleConfig (the layer) and labelScale (its labels).

⚠️ Both are expressed in scale denominators (the X of 1:X), never in MapLibre zoom levels. This is the point the retired zoomConfig got wrong: its name said zoom while the engine read denominators, so { minZoom: 6 } hid layers at every zoom. zoomConfig is therefore rejected outright rather than ignored, and unknown keys inside a scale object are errors too — silently dropping them would leave the layer unconstrained, the same failure one level quieter.

Both fields are optional; absent means no constraint. Accumulator contract — see validateStyleRules.