fix: iron-cauldron, campfire, usd-export-evaluation-mode and gn-modifier-inputs quality pass (#234)

* fix: iron-cauldron quality pass, bellied pot and a bail that threads its ears

The pot was a quadratic from a 28 mm tip; it is now a superellipse belly on
a flat base (pot form, exit 19, --pointed-pot). The ear rings stood in the
bail's plane so the bail ran through their tubes; they lie flat now and the
bail threads them, ends hooking outward (exit 17, --edge-on-ears). Cast
iron, per-pole wood, temp glb removed.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

* fix: campfire quality pass, fieldstones instead of a kerb

Each ring stone is a lofted chamfered lump with a seeded belly, offset and
crown; beds stay flat so the courses still seat. Stone variation budget
(exit 20, --uniform-stones). Fieldstone, wood and ember materials; temp glb
removed.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

* fix: usd-export-evaluation-mode presentation, ingots rest on the floor

Render path only: both subdivided balls hovered 0.16 m above the floor;
each now rests on z = 0 from its evaluated vertices. Brighter key.
Contract and exit codes unchanged on 4.5.11, 5.1.2 and 5.2.1.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

* fix: gn-modifier-inputs presentation, cubes no longer interpenetrate

Layout and render only: XS overlapped the 2 m and 3 m cubes by 0.2 m; they
now stand 0.5 m apart. Frontal camera, duller finish. The check reads only
Z extents; contract and exit codes unchanged on 4.5.11, 5.1.2 and 5.2.1.
Also regenerates the gallery index for all four items.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

* docs: showcase conventions for threaded rings, vessel form and varied stones

From the iron-cauldron and campfire passes.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

---------

Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: TMHSDigital

README.md

@@ -112,7 +112,7 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
   <a href="showcase/shipping-crate/"><img src="showcase/shipping-crate/preview.webp" width="24%" alt="Shipping crate: a wooden slat crate with iron corner brackets on a dark studio floor, warm wedge on the back wall" /></a>
   <a href="showcase/stone-well/"><img src="showcase/stone-well/preview.webp" width="24%" alt="Stone well: a round brick well with a shingled pyramid roof on posts, rope and bucket, on a dark studio floor" /></a>
   <a href="showcase/wooden-barrel/"><img src="showcase/wooden-barrel/preview.webp" width="24%" alt="Wooden barrel: a 20-stave wine-cask with a head of four boards, chord-lofted iron hoops, and a bung on a dark studio floor" /></a>
-  <a href="showcase/campfire/"><img src="showcase/campfire/preview.webp" width="24%" alt="Campfire: a two-course stone fire ring with a tripod of logs on a dark studio floor, warm wedge on the back wall" /></a>
+  <a href="showcase/campfire/"><img src="showcase/campfire/preview.webp" width="24%" alt="Campfire: a two-course ring of rounded fieldstones around a tripod of logs and glowing ash on a dark studio floor, warm wedge on the back wall" /></a>
   <a href="showcase/market-stall/"><img src="showcase/market-stall/preview.webp" width="24%" alt="Market stall: a timber frame with post feet, slatted counter, rafters, and a striped awning on a dark studio floor, warm wedge on the back wall" /></a>
   <a href="showcase/street-lantern/"><img src="showcase/street-lantern/preview.webp" width="24%" alt="Street lantern: an iron post with brass collars, a braced arm, and a muntined amber cage on a dark studio floor" /></a>
   <a href="showcase/treasure-chest/"><img src="showcase/treasure-chest/preview.webp" width="24%" alt="Treasure chest: a slatted wooden chest with iron bands, corner brackets, and an open lid on a dark studio floor" /></a>
@@ -132,7 +132,7 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
   <a href="showcase/wooden-bucket/"><img src="showcase/wooden-bucket/preview.webp" width="24%" alt="Wooden bucket: a coopered pail with a three-strand rope bail through iron ear rings and chord-lofted iron hoops on a dark studio floor" /></a>
   <a href="showcase/wall-torch/"><img src="showcase/wall-torch/preview.webp" width="24%" alt="Wall torch: a dressed stone plaque with an iron sconce, wooden haft, and flame on a dark studio floor" /></a>
   <a href="showcase/tavern-stool/"><img src="showcase/tavern-stool/preview.webp" width="24%" alt="Tavern stool: a round wooden seat on turned splayed legs with stretchers and iron ferrules on a dark studio floor" /></a>
-  <a href="showcase/iron-cauldron/"><img src="showcase/iron-cauldron/preview.webp" width="24%" alt="Iron cauldron: a bulged iron pot hanging from a timber tripod on a dark studio floor" /></a>
+  <a href="showcase/iron-cauldron/"><img src="showcase/iron-cauldron/preview.webp" width="24%" alt="Iron cauldron: a round-bellied cast-iron pot hanging by its bail from a timber tripod on a dark studio floor" /></a>
   <a href="showcase/wooden-ladder/"><img src="showcase/wooden-ladder/preview.webp" width="24%" alt="Wooden ladder: a raked timber ladder with six rungs and iron shoes on a dark studio floor" /></a>
   <a href="showcase/hay-bale/"><img src="showcase/hay-bale/preview.webp" width="24%" alt="Hay bale: a bound straw bale with two sisal twine belts on a dark studio floor" /></a>
   <a href="showcase/crate-stack/"><img src="showcase/crate-stack/preview.webp" width="24%" alt="Crate stack: three slatted shipping crates stacked and yawed, each with iron corner straps and runners, on a dark studio floor" /></a>
@@ -145,7 +145,7 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
 
 [`wooden-barrel`](showcase/wooden-barrel/) — procedural 20-stave wine-cask with boarded, croze-seated heads and chord-lofted hoops through the same pipeline. Falsifiers `--round-band` exits 18, `--one-piece-head` exits 17.
 
-[`campfire`](showcase/campfire/) — procedural cobble ring, logs, and ash through the same pipeline. Falsifier `--skip-decimate` exits 9.
+[`campfire`](showcase/campfire/) — procedural fieldstone ring, logs, and ash through the same pipeline. Falsifiers `--skip-decimate` exits 9, `--uniform-stones` exits 20.
 
 [`market-stall`](showcase/market-stall/) — procedural timber stall with striped awning and counter through the same pipeline. Falsifier `--skip-decimate` exits 9.
 
@@ -185,7 +185,7 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
 
 [`tavern-stool`](showcase/tavern-stool/) — procedural tavern stool with turned legs, stretchers, and iron ferrules through the same pipeline. Falsifier `--skip-decimate` exits 9.
 
-[`iron-cauldron`](showcase/iron-cauldron/) — procedural hanging iron cauldron on a timber tripod through the same pipeline. Falsifier `--skip-decimate` exits 9.
+[`iron-cauldron`](showcase/iron-cauldron/) — procedural round-bellied iron cauldron on a timber tripod through the same pipeline. Falsifiers `--skip-decimate` exits 9, `--pointed-pot` exits 19.
 
 [`wooden-ladder`](showcase/wooden-ladder/) — procedural timber ladder with raked stiles, rungs, and iron shoes through the same pipeline. Falsifier `--skip-decimate` exits 9.
 
@@ -450,7 +450,7 @@ three. `--assume-distinct-names` is red only on 5.2.
 </tr>
 <tr>
 <td width="46%" valign="middle">
-<a href="examples/usd-export-evaluation-mode/"><img src="examples/usd-export-evaluation-mode/preview.webp" alt="USD export evaluation_mode: two steel SUBSURF cubes on a dark studio floor — left faceted viewport tessellation, right smoother render tessellation, warm wedge on the back wall" /></a>
+<a href="examples/usd-export-evaluation-mode/"><img src="examples/usd-export-evaluation-mode/preview.webp" alt="USD export evaluation_mode: two steel SUBSURF cubes resting on a dark studio floor — left faceted viewport tessellation, right smoother render tessellation, warm wedge on the back wall" /></a>
 </td>
 <td valign="middle">
 
@@ -562,7 +562,7 @@ verts = 72, faces = 54, and `Set Material` carries the lime accent.
 </tr>
 <tr>
 <td width="46%" valign="middle">
-<a href="examples/gn-modifier-inputs/"><img src="examples/gn-modifier-inputs/preview.webp" alt="GN modifier inputs: three cubes in teal, copper, and coral scaled to 1, 2, and 3 meters by a shared Geometry Nodes tree, proving per-modifier Scale writes land on 5.2 RNA and on 4.5 dict assignment" /></a>
+<a href="examples/gn-modifier-inputs/"><img src="examples/gn-modifier-inputs/preview.webp" alt="GN modifier inputs: three separate cubes in teal, copper, and coral scaled to 1, 2, and 3 meters by a shared Geometry Nodes tree, proving per-modifier Scale writes land on 5.2 RNA and on 4.5 dict assignment" /></a>
 </td>
 <td valign="middle">