7a4e5eb99d
Records the tap/binding contract: taps are the output-side twin of input_roles (C26), resolved and hoisted at compile, bound run-mode-aware via a caller-built sink (engine stays aura-core-only), recorded on the single run and inert in a sweep. Documents the deliberate DCE-deferral — build-time elision now, chain-pruning when DCE (C23) lands — and the unbound-is-inert non-error asymmetry vs a mandatory input role. refs #282