Build a unified payroll data warehouse by pulling normalized pay statements from Finch across multiple employer payroll providers

Steps

1. Enumerate all connected employer tokens and for each, call GET /employer/payment to list payroll payment runs with pay_period and pay_date metadata
2. For each payment, call POST /employer/pay-statement with the payment_ids array to retrieve individual employee pay statement line items in bulk
3. Normalize earnings, deductions, and taxes arrays from each pay statement to a canonical schema, resolving provider-specific type codes to standard categories
4. Load normalized records into a data warehouse partitioned by employer, pay_date, and employee_id for cross-employer analytics
5. Implement incremental refresh by filtering GET /employer/payment by start_date and end_date to fetch only new pay runs since the last sync