CVE-2026-40070: bsv-sdk and bsv-wallet persist unverified certifier signatures in acquire_certificate (direct and issuance paths)

BSV::Wallet::WalletClient#acquire_certificate persists certificate records to storage without verifying the certifier’s signature over the certificate contents. Both acquisition paths are affected:

• acquisition_protocol: 'direct' — the caller supplies all certificate fields (including signature:) and the record is written to storage verbatim.
• acquisition_protocol: 'issuance' — the client POSTs to a certifier URL and writes whatever signature the response body contains, also without verification.

An attacker who can reach either API (or who controls a certifier endpoint targeted by the issuance path) can forge identity certificates that subsequently appear authentic to list_certificates and prove_certificate.