Paired cocoon commit: 19c714a61808286973ee6b5351009cf450c0bab2
  (erigontech/cocoon @ feat/node-explorer → cocoon-releases, tag demo-0.0.2)

Highlights since demo-0.0.1:
- Caplin sole-producer warm resume: persist head state each slot (dev) + on graceful
  shutdown, anchor on the persisted checkpoint, replay to the true head on restart.
- devvalidator: SSZ bitlist sentinel on dev attestations; commitment marker advance on
  empty blocks.