Verify supplied v15 custom map scene preparation and document format support

docs/SKATE-MAPS.md

@@ -15,7 +15,7 @@ error and do not silently load the default level instead.
 
 | Data | Current support |
 | --- | --- |
-| SKATE01–14 records | Reader supports the documented layouts and raw, zlib and Zstandard blocks. |
+| SKATE01–15 records | Reader supports raw, zlib and Zstandard blocks, plus v15 compressed materials, filtered RGBA, vertex streams, delta indices, indexed collision and backward texture references. |
 | SKATE15+ | Rejected with a version error. V15's additional storage transforms are not implemented. |
 | Visual geometry | Authored positions, triangle winding, normals, UV0/UV1 and material groups. Packed v12+ tangent frames are reconstructed. |
 | Embedded materials | Albedo, normal, ORM, emissive, alpha mask/blend and indirect lightmaps. Lightmap RGB is decoded as `encoded² * 4` into half-float textures. |

docs/custom-map-lighting.md

@@ -73,3 +73,11 @@ directly into the worktree's ignored private output using the shared Cargo
 cache. All six focused CPU tests passed: `map_render::tests` (3),
 `retail_character::tests` (2), and `camera::environment_tests` (1). These checks
 do not validate GPU appearance; use the visual checklist above.
+
+SKATE15 loading is also covered by ten data-reader tests (including legacy
+versions, both compression codecs, all storage transforms, texture references
+and malformed input). A user-supplied v15 custom map passed the ignored CPU
+`supplied_custom_map_prepares_and_retires` check: decoding, runtime validation,
+material/mesh preparation, publication, custom-light classification and scene
+retirement. Supply `SKATE_TEST_CUSTOM_MAP` and `SKATE_TEST_CUSTOM_ASSETS` to run
+that check on another local custom map; no user map bytes are committed.