Define and implement what happens to a PQS knob's minFcv annotation once that FCV drops out of the binary's supported range. Today, QueryKnobRegistryBuilder::addFromServerParameter invariants that every PQS-settable knob has minFcv set; dropping the now-vestigial annotation would trip that invariant. Pick a policy (drop the annotation and relax the invariant, keep the annotation indefinitely, or another option) and apply it consistently to the registry, sanitize path, and validation.