A runtime carries one vendor's providers, only one loads per process,
and a device can now hold several: the package's OpenVINO or WebGPU
build, a CUDA build the user fetched, the distribution's ROCm build.
`api::install` opens each it finds, lists its providers with
GetAvailableProviders, and installs the one scoring highest against the
GPUs `hardware::detect` reads from files — a vendor rung on its own
vendor's GPU above OpenVINO on an Intel one above the generic WebGPU
rung above a CPU-only build. Equal scores keep the old first-found
order, and DARKROOM_ORT_DIR still wins outright. The losers stay mapped
rather than unloaded.
The Linux fingerprint now names the OpenCL drivers too, so installing
Intel's re-probes. `ladder` takes DARKROOM_ORT_DIRS to show the choice.
dtourolle
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