feat(editor): add --gen-mesh-workbench crafter table

62nd procedural mesh primitive. A blacksmith / crafter
workbench built from axis-aligned boxes (uses the new
cli_box_emitter helper plus the new cli_arg_parse helpers
for all 7 optional dimension args):

  • flat top slab spanning length × depth at topT thickness
  • 4 corner legs sized so their outer faces line up with
    the top edges (post-style, no overhang)
  • optional vise box at the +X end of the top — set
    viseSize=0 for a bare bench
  • optional raised tool tray along the +Z back edge —
    set trayH=0 to omit

Pairs naturally with --gen-mesh-anvil (existing) for
blacksmith forge scenes, and --gen-mesh-cauldron for
alchemist labs. Default 1.6×0.7×0.85 m bench reads at
realistic adult-human working height.

Watertight under weld (verified via --info-mesh-stats:
126 manifold edges, 0 boundary, 0 non-manifold).

tools/editor/cli_help.cpp

@@ -236,6 +236,8 @@ void printUsage(const char* argv0) {
     std::printf("                         Chimney: rectangular brick shaft topped by a slightly wider rain-cap (default 0.45/0.45/1.8/0.10/0.05)\n");
     std::printf("  --gen-mesh-bedroll <wom-base> [length] [radius] [sides] [pillowSize]\n");
     std::printf("                         Bedroll: horizontal closed cylinder along Z axis with optional pillow box at +Z (camp set dressing)\n");
+    std::printf("  --gen-mesh-workbench <wom-base> [length] [depth] [height] [legR] [topT] [viseSize] [trayH]\n");
+    std::printf("                         Workbench: 4-legged top slab with optional vise at +X end and back tool tray (blacksmith / crafter)\n");
     std::printf("  --gen-mesh-table <wom-base> [width] [depth] [height] [legThick] [topThick]\n");
     std::printf("                         Table: flat top slab on 4 corner legs (default 1.6/1.0/0.85/0.10/0.06)\n");
     std::printf("  --gen-mesh-lamppost <wom-base> [poleH] [poleT] [baseSize] [lanternSize] [lanternH]\n");