Cram test

OCaml/Dune-style shell transcript test. In Ship, files or directories with a .t suffix are first-class cram session tests under ship test — preferred for CLI behavior, diagnostics, formatter output, and intentionally failing programs.

Compiler run.t suites are a separate Cargo-harness layer and are never discovered by product ship test. A command must exit 0 unless the line directly above it declares # ship-exit: N; any other status fails the case. See ../07-testing.md for the promotion workflow (just promote, filters, hole vs negative vs stub).