Replace the zero-entropy fallback with a deterministic consensus-bound
digest so every RNG-enabled ledger carries usable entropy:
- sha512Half(HashPrefix::entropyFallback, prevLedgerHash, baseTxSetHash,
seq) — all inputs are already consensus-agreed at injection time, so
no new agreement machinery is needed and the digest is identical on
every node building the same ledger
- new sfEntropyTier (UINT8) on the ttCONSENSUS_ENTROPY pseudo-tx and
ConsensusEntropy ledger entry: EntropyCount says how many validators
contributed, EntropyTier says which gate the result passed
(validator_quorum vs consensus_fallback; participant_aligned reserved)
- the fallback digest derives from the BASE (pre-injection) tx set hash
to avoid circularity; entropy pseudo-tx dedup is now type-based since
an explicit-final synthetic set can carry a pseudo-tx whose txID
implicit nodes cannot re-derive
- unparseable-entropy-set residual now falls back instead of skipping
injection, so a fresh ConsensusEntropy entry exists every ledger
- CSF Peer mirrors the fallback analog; sims assert deterministic
non-zero fallback digests across same-LCL peers
- testnet scenarios updated: degraded windows expect labeled fallback
entropy, never validator-tier
The fallback tier is user-influenceable via tx submission (quiet-ledger
grinding) and is labeled accordingly — hook-facing gating lands with the
min_tier/min_count API change.
