My prior commit overwrote tests/mutation_tests.py wholesale instead of
noticing it already belongs to docs/item-provenance-cut.md (this
branch's primary cut, run by a concurrent session sharing this working
tree). Restored it byte-for-byte from 1fdf8151 and moved the
addressables-cut mutation coverage to its own
tests/mutation_tests_addressables_cut.py, since that harness's
runner only knows how to drive `dotnet test` against a source-anchor
mutation and has no path to a Unity batchmode check, which
EngineAssetCheck requires.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>