feat(editor): add --gen-texture-scratched-metal worn-surface

77th procedural texture: base metal color overlaid with N
short angled line segments brightened against the base.
Each scratch is a hash-derived (cx, cy, length, angle)
segment drawn via integer-stepped line walking from
-len/2 to +len/2 along the angle.

Useful for weathered armor, worn weapon blades (especially
old swords / axes that have seen real use), well-used metal
tools, salvaged hull plating, ancient relic surfaces,
dwarven heirloom finishes.

Default 100 scratches at maxLen=24 gives a moderately worn
look on 256x256; bump scratchCount + maxLen for a heavily
battle-scored aesthetic. Deterministic from seed.

tools/editor/cli_help.cpp

@@ -187,6 +187,8 @@ void printUsage(const char* argv0) {
     std::printf("                         Dewdrops: scattered translucent water drops with radial brightness (grass / glass / leaf surfaces)\n");
     std::printf("  --gen-texture-pinwheel <out.png> <aHex> <bHex> [sectors] [W H]\n");
     std::printf("                         Pinwheel: alternating colored triangular wedges radiating from center (mandala / wind-rose / wheel inlay)\n");
+    std::printf("  --gen-texture-scratched-metal <out.png> <baseHex> <scratchHex> [scratchCount] [maxLen] [seed] [W H]\n");
+    std::printf("                         Scratched metal: base color overlaid with N angled hash-derived line segments (worn armor / blades)\n");
     std::printf("  --add-texture-to-zone <zoneDir> <png-path> [renameTo]\n");
     std::printf("                         Copy an existing PNG into <zoneDir> (optionally renaming it on the way in)\n");
     std::printf("  --gen-mesh <wom-base> <cube|plane|sphere|cylinder|torus|cone|ramp> [size]\n");