The C# cases and the TS assertions are here; the vector file is written from the reference in the next commit, so the
slot-nil tests of both runtimes fail at this commit.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Held to tests/vectors/slot-nil/reads.msgpack, written by the C# reference (SlotNilVectorTests): every accepted row
rewrites to the reference's bytes, nil in an int slot is refused. 94a26431c000c0 round-trips byte-identical.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>