BS1-BS5 pin plan 02 task 1's behavior before it exists: the build script
must be landmark-free in stripped code, run ONE contractGraph stage into
the ch: encode input, print the full measured CH stats block (D-08/D-09),
keep the 1-80 MB D-01 envelope single and unchanged, and decode the
committed ARG3 fixture green via --check with CH facts. BS1/BS2/BS3/BS5
fail against the current landmark-era script (which cannot even load —
landmark.ts was deleted in 08.1-01).
