feat(editor): add --gen-mesh-chalice ceremonial goblet

82nd procedural mesh primitive. 3-tier ceremonial chalice:

  • foot — wide flat base disc (the goblet's footprint on
    the table)
  • stem — thin tall connecting column (the holding-grip)
  • bowl — wider shallow cup at the top

Validates that stemR < both footR and bowlR so the
silhouette always reads as the classic wide-narrow-wide
goblet shape rather than a degenerate cylinder stack.

Three more primitives that consume the addClosedCylinderY
helper this batch (lantern + chalice from the previous
two commits + this), pattern is now well-established.

Useful for chapel altars, treasure rooms, royal-court
banquet tables, ritual / cult scenes, dwarven mead halls,
fairy-tale storybook props. Watertight under weld
(verified 252 manifold edges, 0 boundary, 0 non-manifold).

Milestone: kArgRequired now reaches 420 documented flags.

tools/editor/cli_arg_required.cpp

@@ -61,7 +61,7 @@ const char* const kArgRequired[] = {
     "--gen-mesh-hitching-rail", "--gen-mesh-pillar-row",
     "--gen-mesh-statue-base", "--gen-mesh-bird-bath",
     "--gen-mesh-planter-box", "--gen-mesh-urn", "--gen-mesh-candle",
-    "--gen-mesh-lantern",
+    "--gen-mesh-lantern", "--gen-mesh-chalice",
     "--gen-camp-pack", "--gen-blacksmith-pack", "--gen-village-pack",
     "--gen-temple-pack", "--gen-graveyard-pack",
     "--gen-garden-pack", "--gen-dock-pack", "--gen-tavern-pack",