v0.40.7-rc1: mlx: deduplicate CUDA runtime payloads (#17956)

• Deduplicate MLX CUDA runtime payloads

Move CUDA libraries shared by the GGML and MLX backends into the sibling CUDA payload, and teach in-process and subprocess MLX loading to resolve that packaged dependency directory.

Keep MLX-private libraries and JIT headers in the MLX overlay, include the full OpenBLAS Fortran runtime closure, and verify those dependencies in release packaging.

• address comments