Create Bank Account

Declare a bank account for an existing company — accountant (or admin).

Until now only onboarding and the statement importer could create one, so an established tenant had no way to gain a bank account over the API. Same get-or-create-by-IBAN seam as both: ownership lands declared (never the pending matching-hold), a duplicate IBAN reuses + enriches the row, and a given ledger_account_number marks the chart code bank + creates the gl_bank_account bridge at once.