- The changelog's 4.3.0 section loses "(unreleased)": a payment's change goes
  to a fresh change-chain address, and the change chain counts its own index
  (zjyu).
- pubspec 4.3.0; README installs libspiffy ^4.3.0.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>