[EWA] Implement real-time balance checks before repayment attempts

In most EWA setups the key is checking **available balance right before the repayment attempt**, not just when the advance is issued. Teams usually combine balance data with recent transaction patterns to estimate whether the debit will clear. If the balance looks tight, the system delays the debit or reduces the repayment amount. The bigger issue is data quality. Raw bank feeds can be messy, so normalizing transactions and identifying income and recurring outflows first makes the affordability checks much more reliable.