Rename the internal ULP child-build marker to __ULP_BUILDV2 so component CMake files make the build-system scope explicit.
Document that the marker is currently set only by the IDF_BUILD_V2 ULP child path.
Route ulp_embed_binary() through a built-in CMake v2 default ULP project instead of generating a compatibility project with a synthetic main component.
Attach legacy ULP sources directly to the ULP executable, pass the parent component include view through the existing ULP_S_SOURCES/COMPONENT_* channel, and remove the generated legacy project templates plus the component path ownership validation bypass they required.
Update the build-system coverage to assert that the builtin child project builds and rebuilds when parent-owned ULP sources change.
Allow the reconfigure test to assert the buildv2 activation message when pytest runs with --buildv2.
Make the ULP API probe use CMake-friendly forward-slash paths and an explicit ULP toolchain/custom-toolchain setting so the direct cmake configure works on Windows as well as Linux.
Renz Bagaporo