ACI-035: Retire by Deletion

Thesis

Retire a mechanism by deleting it: send anything still wanted to a typed, loud absence or to a replacement that lands in the same commit or release, never behind a shim, and prove the change with mechanical comparisons calibrated on a known-good case. Rebuild a capability the owner still wants before the old one goes, and write down in advance where the new version may differ, because the old suite passing certifies only what it asserts. Zero references shows that nothing refers to a thing, not that nothing needs it.