feat(editor): add --gen-mesh-stove pot-bellied wood stove

85th procedural mesh primitive. Two-cylinder pot-bellied
stove silhouette:

  • body — wide round Y-axis cylinder (the stove body that
    holds the firebox)
  • chimney — thin tall Y-axis cylinder rising from the top
    of the body (the smoke vent)

Distinct from --gen-mesh-forge (square stone hearth + hood
+ chimney) and --gen-mesh-chimney (just the rectangular
shaft) — stove is the round-cylinder home / workshop
variant for cottages, smithies, alchemist labs, ranger
huts, dwarven mead-hall corner heaters.

Validates that chimneyR < bodyR so the silhouette always
reads as a wider-bottom-with-thinner-stack shape rather
than a flat tube.

Watertight under weld (verified 192 manifold edges, 0
boundary, 0 non-manifold).

tools/editor/cli_arg_required.cpp

@@ -68,6 +68,7 @@ const char* const kArgRequired[] = {
     "--gen-mesh-planter-box", "--gen-mesh-urn", "--gen-mesh-candle",
     "--gen-mesh-lantern", "--gen-mesh-chalice",
     "--gen-mesh-standing-torch", "--gen-mesh-scroll-case",
+    "--gen-mesh-stove",
     "--gen-camp-pack", "--gen-blacksmith-pack", "--gen-village-pack",
     "--gen-temple-pack", "--gen-graveyard-pack",
     "--gen-garden-pack", "--gen-dock-pack", "--gen-tavern-pack",