Closed-set typed enum for the two dep-list author-surface axes every
top-level crate::Caixa carries — the runtime-closure :deps slot
(Prod) and the dev-only-closure :deps-dev slot (Dev). Every
substrate consumer that dispatches on “which of the two dep-lists”
(the feira add mutation head, the future per-cluster dev-closure-
audit overlay the M4 CR materializer resolves per-CR, the future
caixa app graph per-list dep summary, every future
Caixa::push_dep / Caixa::deps_by_list typed-method dispatch a
caller reaches for) reads through this enum rather than through a
bare &'static str — the closed-set is expressed at the type layer,
so a future third dep-list axis (a :deps-build build-only closure
once the substrate grows cross-artifact heterogeneous dep-graphs,
per CAIXA-SDLC §I) is one variant plus one arm per method and the
compiler enforces exhaustiveness on every consumer’s match arms.