feat(editor): add --gen-texture-spider-web radial-ring pattern

39th procedural texture: classic geometric spider web — N
radial spokes plus M concentric polygonal rings centered on
the image. Spoke pixels are detected by angular distance to
the nearest spoke scaled by radius, so spokes stay constant
pixel width regardless of how far they reach.

Useful for haunted house decals, dungeon corner overlays,
witch-hut interiors, magical-trap ground markers. Defaults
to 8 spokes (every 45 deg) and 5 evenly-spaced rings.

tools/editor/main.cpp

@@ -166,6 +166,7 @@ int main(int argc, char* argv[]) {
         "--gen-texture-scales", "--gen-texture-stained-glass",
         "--gen-texture-shingles", "--gen-texture-frost",
         "--gen-texture-parquet", "--gen-texture-bubbles",
+        "--gen-texture-spider-web",
         "--validate-glb", "--info-glb", "--info-glb-tree", "--info-glb-bytes",
         "--validate-jsondbc", "--check-glb-bounds", "--validate-stl",
         "--validate-png", "--validate-blp",