Follow-up to #769: applies the same fetch-on-open + resolveAccount pattern to
BulkBookDialog (manual tab bank-leg pre-fill) and BookDirectlyDialog (settlement
line in buildPrefillLines). Both dialogs now fetch /api/cash-accounts when they
open, gate the pre-fill on the fetch resolving, and resolve the correct BAS
ledger account per transaction instead of always emitting '1930'.
Adds lib/cash-accounts/resolve-account.ts (cherry of the utility from #769)
since that PR is not yet merged into main.
Signed-off-by: Jonas Flodén <jonas@floden.nu>