Fetch an employee's wage tax card from Vero

NOT available to API keys — requires an interactive admin/approver session. Fetches the wage tax card for one actual or future payday, applies normalized authority facts through the audited payroll primitive, and returns the refreshed workspace for the payday's month. The server selects the Vero environment and reads the employee identity from tenant-scoped payroll state; neither can be supplied in this request.