Run the memory-evidence profile's adversarial cases, which nothing was running

[Silentpartnercoding]

PR #29 shipped interop/memory-evidence-profile-v0.1/validate.py with four examples and eight adversarial rejection cases. It works. Nothing executed it — not the test suite, not CI, not the Makefile.

Eight adversarial cases that never run are eight cases that cannot fail — the defect this programme spends most of its time finding elsewhere. It shipped in the same session that merged a checker for exactly this shape.

How it was found: the test count. Nine files arrived and the suite did not move. A test count that does not change when tests arrive is the signal.

Three tests

1. Runs the validator; requires it to pass its own corpus.
2. Requires the adversarial corpus to be non-empty — "all cases rejected" is trivially true of an empty list.
3. The one that matters: calls schema_validate and validate_semantics directly and requires the validator to reject a malformed record. A validator that accepted everything would satisfy a check that only asks whether the program exits cleanly, and its eight rejections would mean nothing.

An earlier draft of #3 skipped when it could not find an entry point named validate or check. A skipped test is barely a test, so it now uses the real entry points.