Provenance across the boundary, and the demotion that has to stay visible

Read the rest of obSCEne's docs rather than only the protocol - OUTPUT.md defines the record format the corpus is written in, and it grades every result.

Both projects grade their facts and the vocabularies do not match. The probe writes assumed, derived, spec, documented, hardware; this project writes published, measured, guest-observed, assumed. orbistoun-probe now parses res records, keeps the probe's word verbatim, and maps at the point of use rather than on arrival - the original is what a later reader needs when a mapping turns out to have been too generous.

The mapping is hardware -> measured, spec/documented/derived -> published, assumed -> assumed. With one condition that is the whole point: a hardware result is only measured if the hardware was the target. A value observed on a stand-in is measured for that part and an approximation for this one, so it is demoted to assumed.

Thirteen tests now, all green.

Surprises

derived should not be downgraded, and the conservative instinct says otherwise. It maps to published because this project's own definition of published explicitly covers the tree the target C library derives from. Under-reporting a grade is not free: it makes a fact indistinguishable from a guess, and the entire accounting exists so the two can be told apart. Being careful in the wrong direction is still being wrong.

Clippy asked for the mapping to be made worse. hardware-on-a-stand-in and assumed reach the same grade, so match_same_arms wanted them merged - but they arrive there for opposite reasons, one demoted and one never claiming anything. Merging deletes the only place the demotion is visible, leaving a mapping that reads as though it never downgrades. Allowed with a reason rather than collapsed.

The record format documents its own drift, and it was aimed at parsers like this one. Four record kinds had gained a field the table did not list and five were missing entirely; a parser written against the documentation would have been wrong about half the stream. So an absent provenance is absent, never defaulted - a record predating the field claims nothing, and inventing a grade for it is the same error as recording a value for a call that died.