July counterparty nested-signature recovery

Run offline:
  PYTHONDONTWRITEBYTECODE=1 python3 verify_nested_signatures_offline.py --check

The helper uses the standard library and the unchanged public_signature_core.py.
It sends no requests, signs nothing and derives no private material. It checks
all 51 nested signatures against original raw financial calldata, receipts and
headers, then checks the retained historical owner()/ERC1271 responses.

HISTORICAL-CALL-REQUESTS.json lists 47 owner and 51 validation calls. The separate
fetch_historical_corroboration.py is optional read-only collection code; it reuses
the existing capsule unless explicitly called with --refetch. Its raw capsule
retains 16 failed HTTP429 attempts as well as all 98 eventual successful results.

claimedSigner is the wallet contract for these signature type 3 orders.
nestedRecoveredAuthorizingKey and actualRecoveredSigner are the recovered
public key address; matchesClaimedSigner merely records address equality and
is expected to be false for contract-wallet authorization. It is not an invalid
signature finding. Historical checks use execution-block end-of-block state.

FINAL-SUMMARY.json gives factual scope and limits. KEY-CONTRACT-MAP.json is a
compact 34-row contract-to-key view. NESTED-SIGNATURE-RECOVERIES.json contains all
51 checked orders and exact reconstructed nested inputs. The copied ledger
retains the previous 332 standard counterparty signature recoveries; this lane
freshly replays the 51 nested signatures. The combined observed scope has 383
counterparty appearances and 172 distinct authorizing keys. No listed target
address matches. This does not identify a person or exclude unseen accounts.
