refactor(editor): extract 7 newer texture generators into cli_gen_texture.cpp

Moves the Worley/cellular-noise-based texture handlers
(--gen-texture-cobble, -marble, -metal, -leather, -sand,
-snow, -lava) into their own translation unit. Each handler
previously had its own ~33-line copy of the parseHex lambda;
all 7 copies are replaced with a single shared parseHex
helper at file scope.

Older simpler generators (gradient/noise/radial/stripes/dots/
rings/checker/brick/wood/grass/fabric) still live in main.cpp
and will be migrated in subsequent batches.

main.cpp drops 26,286 → 25,494 lines (-792). Behavior
unchanged across all 7 handlers (re-verified).

tools/editor/cli_gen_texture.hpp

@@ -0,0 +1,24 @@
+#pragma once
+
+namespace wowee {
+namespace editor {
+namespace cli {
+
+// Dispatch the procedural texture generator handlers that have
+// been moved out of main.cpp. Currently the 7 newer Worley/
+// noise-based generators:
+//   --gen-texture-cobble  --gen-texture-marble
+//   --gen-texture-metal   --gen-texture-leather
+//   --gen-texture-sand    --gen-texture-snow
+//   --gen-texture-lava
+//
+// Older simpler generators (gradient/noise/radial/stripes/dots/
+// rings/checker/brick/wood/grass/fabric) still live in main.cpp
+// and will be migrated in subsequent batches.
+//
+// Returns true if matched; outRc holds the exit code.
+bool handleGenTexture(int& i, int argc, char** argv, int& outRc);
+
+} // namespace cli
+} // namespace editor
+} // namespace wowee