feat(editor): add --gen-texture-leopard animal-print pattern

45th procedural texture: leopard print spots done as the
union of 4 small overlapping sub-circles per spot. The
sub-circle offsets are jittered per-spot so each spot has
an irregular non-circular silhouette without authoring per-
spot polygons. Two-color (bg + spot) for the classic
leopard look.

Useful for animal-print fabric, fur tiles, druidic robes,
shamanic hide drums, hunter armor textures. Defaults to 60
spots of ~8-px radius across 256×256.

tools/editor/main.cpp

@@ -192,6 +192,7 @@ int main(int argc, char* argv[]) {
         "--gen-texture-spider-web", "--gen-texture-gingham",
         "--gen-texture-lattice", "--gen-texture-honeycomb",
         "--gen-texture-cracked", "--gen-texture-runes",
+        "--gen-texture-leopard",
         "--validate-glb", "--info-glb", "--info-glb-tree", "--info-glb-bytes",
         "--validate-jsondbc", "--check-glb-bounds", "--validate-stl",
         "--validate-png", "--validate-blp",