Assembles the st-vrqu fragment into a 2.3.0 section and deletes it. The
release adds public API (Statifier.Invoke.SyncHandler, its Adapter, and
Statifier.Invoke.Types.from_handlers/1), so ADR-0066 SemVer commitment
makes this a minor release, and the README requirement moves to ~> 2.3.

Prep only, per campaign-023 ruling R-c: the tag and the Hex publish stay
with the operator.

Refs: st-91vx