fix(examples): redesign cross-version-property-delete as two stage lamps lit by their ID property

The old still showed two blank signboards on a stand. The two IDs under
test are now stage-lamp housings (a lathed, finned can) hanging in U-yokes
from one T-stand. After the check has run, the render path reads each
housing's keys(). A lamp that still carries ["accession"] gets an emissive
lens and a real SPOT light along its beam axis, which pools warm light on
its floor placard. A lamp without the property keeps a dark lens and casts
nothing. The placards, set in the bundled DejaVu Sans Mono, carry the code
that produced each state: obj["accession"] = 42 and del obj["accession"].
The check logic is unchanged; it now runs against the lamp housings instead
of plates, and its messages say "lamp".

Evidence (live runs, local):
- E:\Blender-Developer-Tools\.scratch\blender-5.2.1-windows-x64\blender.exe
  (Blender 5.2.1 LTS): check-only exit 0 (property_unset
  TypeError='Object.property_unset("accession") not found', keep_has=True
  clear_has=False). --unset-instead exits 7 (clear_has=True), and
  --skip-delete exits 7.
- E:\Blender-Developer-Tools\.scratch\blender-4.5.11-windows-x64\blender.exe
  (Blender 4.5.11 LTS): check-only exit 0 with the same values; --output
  renders the identical scene.
- Framing: fill x=0.588 y=0.794; margins l=0.062 r=0.072 b=0.050 t=0.067.
- Contact sheet (docs/gallery/contact-sheets/cross-version-property-delete-contact-sheet.webp):
  candidate luma 0.214 / stage 0.243 / warmth +0.146 / sat 0.131, against
  armature-bend 0.243/0.192/-0.144/0.237, damped-track-aim
  0.237/0.218/+0.105/0.178, and bmesh-gear 0.236/0.177/+0.303/0.250.
  Warmth is in range. Saturation is low because the housings are black
  powder coat by design; the lit/dark lens contrast carries the thumbnail.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: TMHSDigital

README.md

@@ -790,7 +790,7 @@ remains, sources are gone, and the five part materials merge with every face kep
 </tr>
 <tr>
 <td width="46%" valign="middle">
-<a href="examples/cross-version-property-delete/"><img src="examples/cross-version-property-delete/preview.webp" alt="Cross-version property delete: two brass specimen tags hanging on rods from a dark studio stand — left tag with a cyan emissive enamel inlay (ID property kept), right tag with an empty grey pocket (ID property deleted)" /></a>
+<a href="examples/cross-version-property-delete/"><img src="examples/cross-version-property-delete/preview.webp" alt="Cross-version property delete: two stage lamps on one stand — the left lamp keeps its ID property and glows, lighting a placard reading obj[&quot;accession&quot;] = 42; the right lamp had del obj[&quot;accession&quot;] and stands dark" /></a>
 </td>
 <td valign="middle">
 

docs/gallery/assets/cross-version-property-delete-hero.webp

@@ -1,15 +1,16 @@
 # Cross-version property delete
 
-A pair of machined specimen tags that witnesses the custom **ID-property**
+A pair of stage lamps that witnesses the custom **ID-property**
 delete contract from
 [`cross-version-property-delete.py`](../../snippets/cross-version-property-delete.py)
 and [`custom-properties`](../../skills/custom-properties/SKILL.md) — not the
 snippet's `__main__`, which keys off `context.active_object` and prints
 nothing in `--background`.
 
-The IDs are built with `bpy.data.objects.new`. The Keep tag still carries
-`["accession"] = 42` (emissive enamel). The Clear tag had `del obj["accession"]`
-(empty pocket). Same `del` on 4.5 LTS and 5.x; there is no version branch.
+The IDs are two stage-lamp housings built with `bpy.data.objects.new`. The
+Keep lamp still carries `["accession"] = 42`; the Clear lamp had
+`del obj["accession"]`. Same `del` on 4.5 LTS and 5.x; there is no version
+branch.
 
 **What it witnesses:** `property_unset` is a TypeError on a custom ID key and
 does **not** remove it. `del id_block[key]` does. After factory-empty, there is
@@ -26,22 +27,25 @@ no `active_object`.
 
 ## Staging
 
-The two tags now hang from the stand's bar on steel rods. The bar used
-to run 0.17 m behind the plates with nothing joining them, and the
-"rings" were solid discs, so the plates hung on air. The bar spans both
-plates, the post rises to it, and the base is as wide as what it
-carries. Render path only: the check reads ID properties, never
-geometry.
+Both lamps hang in U-yokes from one T-stand. The render path reads each
+housing's `keys()` after the check has run, so the still is driven by the
+checked IDs, not staged from the expected outcome. A lamp that still
+carries the property gets an emissive lens and a real SPOT light along its
+beam axis, which pools warm light on the placard below it. A lamp without
+the property keeps a dark lens and casts nothing. Each placard is set in
+the bundled DejaVu Sans Mono and shows the line of code that produced its
+lamp's state. Only render-side geometry (stand, yokes, lenses, placards) is
+added in the render path; the check reads ID properties, never geometry.
 
 ## Run
 
 ```bash
 blender --background --python cross_version_property_delete.py --
-blender --background --python cross_version_property_delete.py -- --output tags.png
+blender --background --python cross_version_property_delete.py -- --output lamps.png
 ```
 
 `--skip-delete` and `--unset-instead` are falsification switches: both leave
-the Clear plate tagged and exit 7.
+the Clear lamp tagged and exit 7.
 
 The `--output` render path measures framing against the Layer 1 band via
 `examples/gallery_framing.py` (exit 10 on violation) before writing the still.
@@ -59,8 +63,8 @@ against it. `10` is the shared framing helper.
 | 3 | Custom ID property did not land |
 | 4 | `property_unset` on a custom ID key did not TypeError, or it deleted the key |
 | 5 | `del` did not report removal |
-| 6 | Keep plate lost the ID property |
-| 7 | Clear plate still has the ID property (`--skip-delete` / `--unset-instead` land here) |
+| 6 | Keep lamp lost the ID property |
+| 7 | Clear lamp still has the ID property (`--skip-delete` / `--unset-instead` land here) |
 | 10 | Gallery framing violation |
 | 12 | `--output` produced no file |