chore: keep reference photography local and out of the repository

Reference images are development-only material: licensing is not a gate for
local private use, so they are simply never committed. Art/reference/ is now
gitignored; the licensed status of anything shipped is still recorded in
THIRD_PARTY_NOTICES.md.

Adds Tools/commons_fetch.py, which fetches Wikimedia Commons imagery by search
or exact title and writes a provenance sidecar, plus Docs/reference-notes-hollywood.md
recording what each local set is evidence for.

Art/README.md

@@ -8,12 +8,12 @@ Editable sources and original textures. Exported, game-ready output goes to `Gam
 | --- | --- |
 | `Art/blender/` | `.blend` sources, one file per building or asset family |
 | `Art/textures/` | Original texture sources before baking or compression |
-| `Art/reference/` | Licensed reference photography, development only — see attribution rules |
+| `Art/reference/` | Reference photography, local only, **gitignored — never committed**. Fetch with `Tools/commons_fetch.py`; what it is evidence for goes in `Docs/reference-notes-hollywood.md` |
 
 ## Rules
 
 - Every `.blend` saves with a real-world metric scene scale. No exceptions; scale drift is the main source of import defects.
 - Named export presets only. Record the preset name and its settings next to the asset that used it.
 - Textures enter as a documented source (author, licence, source URL) and are listed in [../THIRD_PARTY_NOTICES.md](../THIRD_PARTY_NOTICES.md).
-- Reference photography stays out of the shipped build. It is evidence, not content, and its licences are recorded before it is committed.
+- Reference photography is never committed and never shipped. It is evidence, not content. Licensing is not a gate for local private development, but anything that would derive from a reference in a shipped asset needs a licensing decision before release.
 - `.blend` files are LFS-tracked and lockable; pull before editing.