Create a bank repo snapshot

Verified staff/service with ledger:repo:read captures immutable current observed repo evidence with requested close-date coverage. This read authority cannot trade, pay money or release collateral. Actor/key replay retains the original source, actual observation date and time, bank legal entity, debt/collateral, exact accounting journals and explicit blockers. Dated accrued interest and original-custodian bid sources must cover the requested close; later current observations do not reconstruct old books. Provider-signed cash remains distinct from independently reconciled actual master-statement evidence. Bridge authority alone grants no all-book capture. Every route requires verified non-API-key authority even locally; customer actors are refused. JSON evidence is one strict object bounded at 5 MiB. Complete responses are bounded at 16 MiB and fail explicitly without truncation.