Generic per-check diagnostic produced by the metatheorem checker. We
flatten the per-checker diagnostic types (TotalityDiagnostic etc.)
into a single shape so the report consumer does not have to know which
underlying checker emitted the message.
Top-level structured report returned by check_metatheorems. The
CLI uses format_report to render it; library consumers can read
the structured fields directly.
Public API: evaluate text, then enumerate every relation that has a
(mode ...) declaration plus matching (relation ...) clauses, and
every definition that has a (define ...) declaration. Each candidate
becomes a metatheorem result.
Render a MetatheoremReport as the same human-readable text the CLI
prints. Useful in tests that want to assert on the rendered output as
well as the structured shape.