feat(editor): add --gen-texture-bamboo jungle-stalk pattern

62nd procedural texture: vertical bamboo stalks with
cylindrical sin² brightness shading + horizontal darker
node bands at regular Y intervals. Each stalk gets a small
hash-derived hue jitter (±15) so adjacent stalks don't
read as a perfect repeat.

Per-pixel logic:
  • 10% horizontal gap between stalks (gapFrac=0.10) →
    visible bg seam between bamboo stalks
  • Inside the stalk, brightness = sin²(insetFraction * π)
    rising from 0 at the stalk edge to 1 at the centerline
  • Every nodeY pixels, a `nodeBand`-tall horizontal strip
    has its brightness knocked down to 2/3 — the segmented
    bamboo joint look

Useful for jungle huts, pandaren / asian-themed architecture,
swamp boardwalks, tropical-tribe weapon trim, brewmaster
zone trim. Default 24-pitch / 64-spacing / 4-band reads as
adult-bamboo at typical 256x256 wall-tile scale.

tools/editor/cli_help.cpp

@@ -157,6 +157,8 @@ void printUsage(const char* argv0) {
     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("  --gen-texture-bamboo <out.png> <bgHex> <bambooHex> [stalkW] [nodeY] [nodeBand] [seed] [W H]\n");
+    std::printf("                         Bamboo: vertical stalks with sin² shading + horizontal node bands (jungle / asian-themed)\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");