Runtime-loaded ROCm/rocBLAS tensor compute site for SIM.
This crate has no ROCm toolkit or link-time dependency. On Linux it validates
the HIP runtime, rocBLAS ABI, and observed AMD `gfx*` target through runtime
evidence, exports a site only when the runtime is present, and accepts only dense
matmul requests that the ROCm provider can execute semantically. Half-family
matmul is enabled only when rocBLASLt evidence is present.