feat(editor): add --gen-texture-lattice diagonal-grid pattern

41st procedural texture: garden trellis / mesh fence done as
two perpendicular sets of diagonal lines (+45° and -45°)
drawn simultaneously across the whole image so they form
diamond-shaped openings between the lines.

Distinct from --gen-texture-herringbone (which alternates
strip orientation): lattice draws both diagonal sets at every
pixel. Useful for trellises, wire mesh fences, dragon-scale
chain mail, decorative window grilles. Defaults to 24-px line
spacing with 3-px line width.

tools/editor/main.cpp

@@ -171,6 +171,7 @@ int main(int argc, char* argv[]) {
         "--gen-texture-shingles", "--gen-texture-frost",
         "--gen-texture-parquet", "--gen-texture-bubbles",
         "--gen-texture-spider-web", "--gen-texture-gingham",
+        "--gen-texture-lattice",
         "--validate-glb", "--info-glb", "--info-glb-tree", "--info-glb-bytes",
         "--validate-jsondbc", "--check-glb-bounds", "--validate-stl",
         "--validate-png", "--validate-blp",