Brummel
8e415dd4b4
Records strategy (b) (codegen-side bookkeeping, no source mutation), why strategy (a) was retired (borrow contracts + desugar re-scrutinise), the moved_slots side table and its consumers (Term::Let close + reuse arm), and the narrow memory-hygiene regression on borrow_only_recursive_list_drop that 18d.4 will close. Also flags 18d.3 as the first iter to ship with an undetected (no valgrind in CI) memory-hygiene regression — accepted with explicit follow-up iter, not papered over.