fix(showcase): treasure-chest and tavern-stool visual quality pass

[TMHSDigital]

Summary

Showcase visual quality pass on treasure-chest and tavern-stool (the two worst remaining from the grindstone/wheelbarrow report). Generators rebuilt; hygiene/joint-fit locked as assertions; heroes re-rendered on 5.2.1 with check_framing (no deviation=).

treasure-chest

Intended size: 0.74 × 0.46 m plan, ~0.35 m to the rim, barrel-vault lid. AABB (0.764, 0.542, 0.691) m.

Defects (inspection sheet, .scratch/qpass/chest/)

1. Lid was a flat sandwich of boxes, not a vault — front ortho, clay_side, three_quarter_a.
2. No hinge hardware — back ortho, joint_hinge.
3. Lock was two cubes on a plate — joint_lock.
4. Slats glued onto solid walls — interior, joint_slat_wall.
5. Bands did not wrap the U — bottom ortho, joint_band_wall.
6. L-brackets floated off the corners — joint_bracket, ortho_left.
7. Feet were cubes hovering or intersecting the floor — ground_contact.
8. Daylight between lid and body at the back — joint_lid_lip, clay_side (exploded biscuits).
9. Spanning stile only had verts at the X ends, so BVH reported a false 8.5 cm hinge gap — diag shells s70 vs s34.

Generator fixes (structural)

• Hollow slatted body is the walls; feet tenon into the bottom; U-wrap bands; nested L-irons.
• Lid is one add_arc_slab barrel vault (not stacked boxes). Overlay slat ribs were dropped after clay_side showed them as a comb.
• Hinge barrels on the back rim; local lid knuckles at the barrel X stations (not a spanning stile).
• Wood-only bevel, then metal paint (bevel was wiping material_index).
• --float-hinge lifts knuckles off barrels without swinging the vault past the AABB.

Hygiene / joint-fit (all three binaries)

Axis	4.5.11 / 5.1.2 / 5.2.1
tris	3852 (was 5724)
hygiene (loose/nonman/doubles/zero-area/ngons/zfight)	0
zmin / 4 feet	0 / 4
hinge_join	0.00700
band_gap	0
collider	176

Falsifiers (same on 4.5.11, 5.1.2, 5.2.1): default 0; --skip-decimate 9; --stray-vert 15; --lift-z 16; --short-legs 16; --float-hinge 17; --narrow-bands 18.

Inspection rounds: 4 generator looks (round-1 original; round-2 rewrite; round-3 vault biscuits; round-4 lofted slab). Framing on 5.2.1: fill y=0.756, margins ok.

Remaining nits (not blocking): lid straps still faceted along the arc; lock staple is two nubs; hinge barrels are boxes; feet are beveled cubes.

tavern-stool

Intended size: 0.34 m seat, 0.47 m high, splayed legs. AABB (0.340, 0.340, 0.470) m.

Defects

1. 16-gon puck seat — ortho_top, seat_top.
2. Legs were stacked cones with kinks — clay_front, ortho_front.
3. Octagon pucks under the feet — joint_ferrule_floor.
4. Whole piece zmin 0.002 — ground_contact.
5. Stretchers punched through the legs — joint_stretcher.
6. Legs clustered under the seat — ortho_top.
7. Splayed wood sawtoothing through a vertical cup — joint_ferrule (round-2).
8. Seat disc classified as a stretcher, so --float-stretchers could not fail — stretcher_join.

Generator fixes (structural)

• Lathed seat (48 segs) and one lofted profile per leg.
• Vertical ferrule cups; wood ends above the cup so the splay does not cut the wall; inner clearance band.
• Stretchers tenon into the legs; classifier excludes the seat disc.
• --float-stretchers omits the rails (named fail 17); --pipe-ferrule is a torus in the bite band.

Hygiene / joint-fit (all three)

Axis	4.5.11 / 5.1.2 / 5.2.1
tris	2528 (was 5396)
hygiene	0
zmin / 4 cups	0 / 4
stretch_join	0
ferrule_bite	−0.00125
collider	396

Falsifiers (same on all three): default 0; --skip-decimate 9; --stray-vert 15; --lift-z 16; --short-legs 16; --float-stretchers 17; --pipe-ferrule 18.

Inspection rounds: 3 (original / rewrite / 48-seg + clearance). Framing on 5.2.1: fill y=0.794, margins ok.

Remaining nits: vertical cup vs splay still shows a crescent of daylight in the close-up; seat rim still a 48-gon if you look.

Test plan

• Default + all falsifiers on 4.5.11, 5.1.2, 5.2.1
• Heroes on 5.2.1 Cycles; framing gate passed (no deviation=)
• CI blender-smoke 5.2 LTS, 4.5 LTS, and labeled 5.1
• Gallery Pages 200 after merge