The subset of a layer entry the style selector needs: its identity and the styles it offers.
Deliberately narrower than the full layer config — the selector never reads geometry or data, so a caller can build one from any layer-shaped object.
Layer id, the key under which the current style is tracked.
Optional
Display name; falls back to the id when absent.
The alternative styles this layer offers. Absent means no style choice is rendered.
The subset of a layer entry the style selector needs: its identity and the styles it offers.
Deliberately narrower than the full layer config — the selector never reads geometry or data, so a caller can build one from any layer-shaped object.