feat(glb): a loader for binary glTF, and images decoded from memory

- Crafter.Asset:GLB. GlbAsset::Load reads a .glb from a file or a buffer:
  - nodes, with their parents;
  - every mesh's primitives: positions, normals, UV0, tangents (computed
    when absent), joints, weights (normalized), u32 indices;
  - skins with their inverse-bind matrices;
  - materials: PBR, emissive strength, transmission, ior, alpha mode;
  - images decoded to RGBA8, and samplers;
  - cameras and KHR_lights_punctual lights;
  - the raw JSON, and the extras of the scene, nodes, materials and lights.
  nlohmann/json 3.12.0 is vendored in lib/; only the implementation sees it.
- A broken file comes back as an error rather than a crash:
  - bad magic, truncation, a sparse accessor;
  - a chunk, view or accessor past its bounds, checked so that nothing
    wraps round, with 32-bit size_t too;
  - a stride outside 4..252, or one its elements overlap in;
  - a reference to something that doesn't exist, or children that form a
    cycle (found stepping through each node once, however deep);
  - a path that isn't a file;
  - an image larger than a texture's 65535 a side.
- TextureAsset::LoadPNGFromMemory decodes an image already in memory.
  LoadPNG refuses images over 65535 a side instead of truncating their size
  (in its float path, past the end of the pixels).
- Tests: GLB.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

interfaces/Crafter.Asset.cppm

@@ -4,4 +4,5 @@
 export module Crafter.Asset;
 export import :Compression;
 export import :Mesh;
-export import :Texture;
+export import :Texture;
+export import :GLB;