Follow-up to #1809: transaction listings now carry cash_account_id, but an
agent had no way to learn which cash accounts exist or which BAS ledger
each maps to. The tool lists cash_accounts (cash_account_id, ledger_account,
name, currency, iban, is_primary, enabled, source), optionally enabled
only. Search-only (catalogVisibility 'search') so tools/list stays inside
its context budget; gnubok_search_tools finds it on "bank account"/"cash
account". Scope transactions:read.
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
