Turkey province boundaries adapted from alpers/Turkey-Maps-GeoJSON:
https://github.com/alpers/Turkey-Maps-GeoJSON/blob/master/tr-cities.json
License: Apache-2.0 (see turkey-provinces.LICENSE).
Changes: projected coordinates, rounded precision, extracted outer rings,
computed label anchors and normalized province names/slugs. Small islands
are preserved; inland polygon holes are omitted for the display mesh.