refactor(editor): extract addBox into shared cli_box_emitter

36 procedural mesh primitives in cli_gen_mesh.cpp each open-
coded the same ~30-line lambda for emitting a flat-shaded
axis-aligned box (per-face vertices for unique normals,
6 faces × 4 verts × 2 tris). Hoist the implementation into
cli_box_emitter.{hpp,cpp} as addFlatBox(WoweeModel&, ...)
with two overloads:

  • addFlatBox(wom, cx, cy, cz, hx, hy, hz)
    center + half-extents form, used by 34 primitives
  • addFlatBox(wom, glm::vec3 lo, glm::vec3 hi)
    lo/hi corners form, used by --gen-mesh-archway and
    --gen-mesh-fence which compute corners directly

Each lambda site collapses from ~30 lines to a 3-line thin
wrapper: cli_gen_mesh.cpp drops from 7374 to 6989 lines.
Output bytes verified identical via --info-mesh-stats
(firepit surface area 2.1100 m² unchanged, vertex/triangle
counts match across firepit/canopy/dock/archway/fence).

Future box-based primitives now opt in by including one
header instead of pasting the lambda again.

tools/editor/cli_box_emitter.hpp

@@ -0,0 +1,33 @@
+#pragma once
+
+#include "pipeline/wowee_model.hpp"
+#include <glm/glm.hpp>
+
+namespace wowee {
+namespace editor {
+namespace cli {
+
+// Append a flat-shaded axis-aligned box to a WoweeModel. The box
+// is centered at (cx, cy, cz) with half-extents (hx, hy, hz). Each
+// of the 6 faces emits its own 4 vertices with the face's outward
+// normal, so adjacent faces don't share normals — exactly what
+// flat shading needs. UVs are 0..1 across each face.
+//
+// Used pervasively by --gen-mesh-* primitives that build meshes
+// from axis-aligned box primitives (firepit stones, dock pilings,
+// canopy posts, woodpile logs, tent walls before the door cutout
+// added one-off triangles, etc.). Hoisted out of cli_gen_mesh.cpp
+// where 36 identical lambdas duplicated this implementation.
+void addFlatBox(wowee::pipeline::WoweeModel& wom,
+                float cx, float cy, float cz,
+                float hx, float hy, float hz);
+
+// Overload taking lower/upper corner positions (lo, hi). Some
+// callers (--gen-mesh-archway, --gen-mesh-fence) compute corners
+// directly rather than center+halfsize.
+void addFlatBox(wowee::pipeline::WoweeModel& wom,
+                glm::vec3 lo, glm::vec3 hi);
+
+} // namespace cli
+} // namespace editor
+} // namespace wowee