* fix(domain): replace bare parser errors with typed codes
OpenStep syntax, canonical JSON digests, managed-graph source checks,
frame fingerprints, and reference-flow invariants threw Error and
published the sentence. Each refusal now carries a code. Tests assert
that code, including OpenStep position, instead of the previous prose.
* test(domain): pin OpenStep refusal codes and positions
The syntax cases accepted any code and any offset. Each container
refusal now expects its code and source position, including the deep
suffix that changes (x from unterminated_array to expected_separator.
Scalar failures stay identical to the pinned decoder.
* test(filesystem): assert OpenStep keyed-archive codes
The deep-suffix keyed archive cases compared ArtifactReaderFailure
message text with the pinned decoder sentence. They now require
reason format and the OpenStep code and source position on the cause.
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Co-authored-by: Cursor Agent <cursoragent@cursor.com>
