docs(assets): 3D-model+texture catalog, glb-gen production path, conventions (T-1050)

Instantiates the five D-244 catalog files (models/textures/artwork/icons/
effects — icons carries the 13 as-built SVGs, stance icons traced to their
consumer and marked final), creates client/assets/models/{furniture,props}
with a schema-documented manifest.json mirroring the character manifest,
fixes glb-gen SKILL.md's stale 'path does not exist' paragraph, and authors
docs/assets/visual/conventions.md: category-first model naming (araminta
ruling), mask sidecars per the character convention, D-235-token-keyed
texture naming, footprint_tiles as manifest metadata. Door-state and
TileSet conventions are recorded as explicit deferrals (Phase-5 owned).
visual/README.md carries both this ticket's count/link updates and
T-1052's palette-section rewrite (shared file, committed here).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/assets/visual/artwork.md

@@ -0,0 +1,41 @@
+---
+title: "Artwork — Visual Assets"
+description: "Flat 2D artwork asset catalog — paintings, flags, billboards, signage, screen content"
+type: design
+status: active
+---
+
+# Artwork — Visual Assets
+
+Flat 2D art — paintings, flags, billboards, signage, screen content — that
+lives as a texture/decal on a flat surface *within* the 3D world. This is one
+of the two flattened-2D exceptions under D-244 (the other is
+[textures.md](textures.md)); it is not a sprite layer.
+
+## Generation Approach
+
+Produced via the `/sprite-gen` skill's **repurposed 2D-artwork role**
+(`renderer/README.md`) — the offline Godot renderer originally built for the
+retired object-sprite pipeline (#541 spike), now serving flat-artwork
+rendering. Camera/lighting/resolution mechanics from that pipeline are
+reused; the "render every entity/object/wall to sprites" framing in
+`renderer/README.md` is legacy and does not apply here.
+
+Output is promoted to `client/assets/artwork/` (per `renderer/README.md`'s
+own note: flat-artwork output goes to `client/assets/textures` or
+`client/assets/artwork`, never `client/assets/sprites/`).
+
+## Assets
+
+| ID | Filename | Status | Type | Notes | Sprint/Ticket |
+|----|----------|--------|------|-------|---------------|
+
+No artwork has entered production yet — this table is intentionally empty at
+initial creation (T-1050).
+
+## Cross-References
+
+- [conventions.md](conventions.md)
+- `renderer/README.md` — repurposed 2D-artwork render pipeline
+- `.claude/skills/sprite-gen/SKILL.md`
+- [D-244](../../../governance/decisions/architecture.md#d-244-asset-rendering--3d-objects-in-world-2d-limited-to-textures--flat-artwork)