Emits a list of red-team cases as a tribunal-shaped dataset YAML.

Targets the specific shape produced by Tribunal.RedTeam.generate/1: each case is %{input: string, metadata: map, expected: map}. The output round-trips through Tribunal.Dataset.load/1.

Not a general-purpose YAML emitter. Handles strings (single- and multi-line), atoms, numbers, maps, keyword lists, and lists of scalars — the value types that appear in red-team case structures.