fix: exclude host-only MemoryUsage.cpp from CUDA compilation (nvcc 12.8.1 + GCC 13 cudafe++ crash)

[Copilot]

set_cuda_build_properties() unconditionally marks every .cpp source as LANGUAGE CUDA, routing pure host-only files like src/MemoryUsage.cpp through nvcc's cudafe++ front-end. On nvcc 12.8.1 with GCC 13 as the host compiler, cudafe++ hits an internal assertion in find_allocated_name_reference while parsing stl_construct.h, aborting the build.

Changes

cmake/kynema-driver-utils.cmake

• set_cuda_build_properties() now accepts an optional ARGN list of host-only source paths
• Those paths are removed from the CUDA sources list and explicitly set to LANGUAGE CXX, bypassing nvcc entirely
• Comment added documenting the nvcc 12.8.1 / GCC 13 cudafe++ crash as the motivation

function(set_cuda_build_properties target)
  # Optional ARGN: host-only source paths kept as LANGUAGE CXX to bypass
  # nvcc/cudafe++, which crashes on GCC 13 headers (nvcc 12.8.1, lexical.c
  # assertion in find_allocated_name_reference).
  set(_host_only_srcs ${ARGN})
  ...
  if(_host_only_srcs)
    list(REMOVE_ITEM _tgt_src ${_host_only_srcs})
    set_source_files_properties(${_host_only_srcs} PROPERTIES LANGUAGE CXX)
  endif()
  set_source_files_properties(${_tgt_src} PROPERTIES LANGUAGE CUDA)
  ...
endfunction()

CMakeLists.txt

• Defines _kynema_host_only_srcs containing src/MemoryUsage.cpp and passes it to every set_cuda_build_properties() call in the CUDA-enabled block
• No change to the CUDA=OFF path