refactor(api): clean root package — interfaces only, metal auto-registered
Root package now contains only:
- mlx.go: package doc + go:generate directives
- textmodel.go: TextModel, Token, Message interfaces
- options.go: GenerateOption, LoadOption functional options
- backend.go: Backend interface, Register/Get/Default/LoadModel
- register_metal.go: build-tagged init() + adapter + memory delegates
- mlx_stub.go: non-darwin fallback
internal/metal/ has its own Token, GenerateConfig, Model types.
register_metal.go adapts between the two via metalAdapter.
Co-Authored-By: Virgil <virgil@lethean.io>
4d1bff3d78