Brummel
09fb5bb113
Adds a per-fn linearity check that runs on every fn whose param_modes are all explicit (Borrow or Own, no Implicit), tracks each binder's consume/borrow state through the AST, and emits two diagnostics with form-A `suggested_rewrites`: - `use-after-consume` — a binder is referenced after it has already been consumed. - `consume-while-borrowed` — a binder is consumed while a borrow of it is still live (sibling arg slot, or an enclosing-fn Borrow param). Fns with any Implicit param skip the check entirely; that's the back-compat lane that keeps every existing fixture green. Pure diagnostic addition: no IR change, no codegen change, no runtime change. Each diagnostic carries a non-empty `suggested_rewrites` whose `replacement` is form-A AILang text (typically `(clone <name>)`). Adds two new public entrypoints to ailang-surface — `parse_term` and `term_to_form_a` — so the round-trip `parse_term(term_to_form_a(t)) ≡ t` is the contract every emitted replacement must satisfy. Tests assert the contract. Linearity pass runs only on modules that typechecked clean (any upstream typecheck error suppresses it for that module — running on partly-defined IR would produce noise). Tests: 3 unit tests in `linearity::tests`, 3 integration tests in `ailang-check/tests/workspace.rs`, 1 serialisation test in `diagnostic.rs`. `cargo test --workspace` green.