test/misc hosts the residual mixed-shape observers (divergence pins,
stamp/stderr probes, .wwi trees) on testenv, wired into test-compiler
beside the sep/xmod/asm families; its rule declares both full
per-stage toolchains plus the wwdump twins for the coming files.
The 689 port keeps the both-driver run-exit-6 backstop and the
per-stage absolute DATAW row count (linker dedup and byte-id sweeps
are both blind to a symmetric double-emit).
