* refactor(litellm-rust): move provider transforms into litellm-core + crate allowlist test
* feat(litellm-rust): ai-gateway absorbs route I/O (io/) with lib+server feature split
* refactor(litellm-rust): point python-bridge at litellm-ai-gateway
* build(litellm-rust): macOS pyo3 dynamic_lookup linker flag for cdylib builds
* docs(litellm-rust): 3-crate map in README/AGENTS + refresh CLAUDE boundary
* refactor(litellm-rust): update workspace members to the three crates