Shared support for hosting ORT-compatible plugins

onnx_light_ort::common_ort_to_light is a static library exposing the initial audited CPU custom-op subset of OrtApi over onnx-light tensors. It supplies opaque adapters for statuses, registration domains, kernel attributes, values and contexts. Custom-op bridge: ORT custom ops called by onnx-light owns loading, descriptor selection and the session/kernel/library lifecycle. The EP bridge remains unimplemented.

OrtApiBase::GetApi accepts only version 18. The full pinned OrtApi layout is preserved; unsupported slots remain null. Supported entries are:

• CreateStatus, GetErrorCode, GetErrorMessage, ReleaseStatus.

• CreateCustomOpDomain, CustomOpDomain_Add, AddCustomOpDomain, ReleaseCustomOpDomain.

• KernelInfoGetAttribute_float.

• KernelContext_GetInputCount, KernelContext_GetOutputCount, KernelContext_GetInput, KernelContext_GetOutput.

• GetTensorTypeAndShape, ReleaseTensorTypeAndShapeInfo, GetTensorElementType, GetDimensionsCount, GetDimensions, GetTensorShapeElementCount, GetTensorMutableData.

• GetTensorMemoryInfo, MemoryInfoGetDeviceType.

These functions implement dense float16, bfloat16, float32 and float64 CPU values. Type queries report the actual tensor type, and output allocation uses the selected descriptor’s output type. Shape and dtype-dependent byte counts are checked before allocating outputs. The component is independent of the outgoing common library and never loads ORT. tests/ort_test_host.h remains separate test infrastructure for outgoing callback units, not this host.

The dependency-contract smoke test is retained alongside the real incoming fixture tests. Select both using the common_ort_to_light CTest label.