Decentralized-sequencing foundation: a shared chain_state crate (two-tier
head/final ChainState, apply_block, AcceptOutcome, StallReason, and the
absorbed channel-consistency machinery), turn-gated block production, the
publisher follow path for adopted/orphaned/finalized peer blocks, and
persistence that keeps disk order equal to apply order under the chain lock.
Rebased onto dev after #600/#606: chain_consistency is absorbed into
chain_state, the sequencer bootstrap's verify_and_reconstruct is re-wired
onto the two-tier ChainState (reconstruction applies channel history
through the final tier and persists via the follow-path primitives), and
test fixtures adopt the SequencerSetup builder extended with
with_bedrock_signing_key.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
