feat(editor): add --gen-mesh-bedroll camp sleeping prop

61st procedural mesh primitive. Builds a bedroll prop:

  • horizontal closed cylinder along the Z axis sitting at
    y = R so it rests on the ground (radius defaults to
    0.16 m, length 1.4 m — adult-human-shaped)
  • optional pillow box at the +Z end (squashed cube,
    pillowSize controls extent)
  • per-segment N-sided cylinder uses the new addVertex
    helper; pillow uses addFlatBox

Set pillowSize=0 for a bare rolled mat. Watertight under
weld (verified via --info-mesh-stats: 90 manifold edges,
0 boundary, 0 non-manifold).

Pairs naturally with --gen-mesh-tent / --gen-mesh-firepit /
--gen-mesh-canopy for outdoor camp scenes — completes the
tent-side camping kit.

tools/editor/cli_help.cpp

@@ -232,6 +232,8 @@ void printUsage(const char* argv0) {
     std::printf("                         Pergola: 4 corner posts + 2 perimeter beams + N cross beams (open lattice top, no panel)\n");
     std::printf("  --gen-mesh-chimney <wom-base> [width] [depth] [height] [capH] [capExtra]\n");
     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-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");