feat(editor): add --gen-mesh-statue-base monument pedestal

76th procedural mesh primitive. Classic 3-tier square
pedestal for statues / monuments / hero memorials:

  • plinth — bottom block, plinthExtra wider per side than
    the body (the foundation that meets the ground)
  • body — tall central pedestal sitting on the plinth
    (where the inscription would go)
  • capital — small wider cap on top of the body (where
    the statue's feet would rest)

Distinct from --gen-mesh-podium (stepped pyramid with
lectern at back) and --gen-mesh-altar (stacked round
discs) — this is the classic single-statue square
pedestal shape.

Useful for town-square monuments, hero-of-the-revolution
memorials, plaza centerpieces, mausoleum interiors,
saint-statue stands. Watertight under weld (verified 54
manifold edges, 0 boundary, 0 non-manifold).

tools/editor/cli_arg_required.cpp

@@ -59,6 +59,7 @@ const char* const kArgRequired[] = {
     "--gen-mesh-archery-target", "--gen-mesh-gravel-pile",
     "--gen-mesh-stone-bench", "--gen-mesh-mine-cart",
     "--gen-mesh-hitching-rail", "--gen-mesh-pillar-row",
+    "--gen-mesh-statue-base",
     "--gen-camp-pack", "--gen-blacksmith-pack", "--gen-village-pack",
     "--gen-temple-pack", "--gen-graveyard-pack",
     "--gen-garden-pack", "--gen-dock-pack",