feat(editor): add --gen-texture-mesh-screen orthogonal grid

61st procedural texture: thin horizontal + vertical wires
forming an axis-aligned grid. Distinct from
--gen-texture-lattice (which uses ±45° diagonals to make
diamond openings) — this gives the right-angle window-
screen / chain-link / sci-fi-grille look.

Tested per-axis: a row is "on a wire" if (y % stride) <
wireW; a pixel falls on a wire if either its row OR its
column tests positive. Result is the unmistakable
orthogonal-mesh appearance.

Useful for window screens, anti-pest grates, fish nets,
sewer grilles, sci-fi vent panels, prison-cell windows,
goblin-workshop catwalks. Default 12-stride / 2-wide
gives a coarse mesh; finer versions read as bug screen.

tools/editor/cli_help.cpp

@@ -155,6 +155,8 @@ void printUsage(const char* argv0) {
     std::printf("                         Camouflage: 2-octave value noise thresholded into hard bg/fg blobs (woodland disruption pattern)\n");
     std::printf("  --gen-texture-snake-skin <out.png> <bgHex> <scaleHex> [cellW] [cellH] [outlineW] [W H]\n");
     std::printf("                         Snake skin: brick-offset diamond scales (L1 metric) with derived dark outline (reptile / dragon hide)\n");
+    std::printf("  --gen-texture-mesh-screen <out.png> <bgHex> <wireHex> [stride] [wireW] [W H]\n");
+    std::printf("                         Mesh-screen: orthogonal H+V wire grid (window screen / chain-link / sci-fi grille)\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");