chore: install blender-skills 1.3.0 for modelling work

94 MIT-licensed skill packs plus their shared references, copied unedited from
the local checkout of github.com/arjun988/blender-skills at commit 8f778d2
(1.2 MB, 269 Markdown files). They are agent instructions, not add-ons; the
pipeline still drives Blender headlessly through bpy, so the optional Blender MCP
server is not required. Provenance recorded in THIRD_PARTY_NOTICES.md and the
version, source, and update procedure in Docs/toolchain.md.

Art/blender/README.md

@@ -2,6 +2,10 @@
 
 Editable `.blend` files. Everything here is regenerable or hand-editable, and every generated file records the exact command that produced it.
 
+## Modelling skills
+
+`.agents/skills/blender-skills/` holds 94 Blender skill packs (MIT, v1.3.0) — `blender-modeler`, `hard-surface`, `uv-workflow`, `collision-proxy`, `archviz`, and so on. They are instructions for the agent, not add-ons, and nothing in the pipeline depends on them. Provenance in `THIRD_PARTY_NOTICES.md`.
+
 ## Blockout
 
 `blockout/blockout-2026-11-06.blend` — OSM blockout for the demo bounds, imported with Blosm from the committed extract. 276 objects, 87 meshes, in collections split by feature (`…_buildings`, `…_roads_secondary`, `…_paths_footway`, `…_roads_primary`, …).