More accurate account numbers, credit unions, and merchant names

A case falls apart if the transactions are filed under the wrong account or the wrong vendor. This round tightens how the extractor reads accounts and merchants.

• Fewer wrong or duplicate accounts. Account-number extraction now runs stricter validation: routing numbers are filtered out by ABA checksum, check-image and reference numbers are rejected, fully redacted values are discarded, and partial masks like ****5454 have their visible digits pulled through. That cuts the false and duplicate accounts that came from noisy or redacted statements.

• Reads credit union statements. Statements are now told apart as credit union or bank using share account terminology, member versus customer language, and NCUA versus FDIC cues. Short share IDs like "Share 08" are detected, validated, and mapped to each transaction, and any share number that doesn't match a real one on the statement gets dropped. Bank statements no longer pick up spurious share numbers at all.

• Consistent merchant names across a case. A vendor-resolution step normalizes merchant names and categories so the same vendor reads the same way everywhere, even on large cases with tens of thousands of transactions.