Add provider field to transactions endpoint

Changes

• Added a new optional string field provider to the schema for the POST /business/data/account-transactions endpoint.
  • This field indicates the provider of the transaction data (e.g., bridge, plaid).
  • The value "MANUAL" is used if the transaction was manually imported.
  • Currently, the field is not an enum and is included in the raw data for context as it may be used in the future.