Populate the PAYER's TIN (EIN) box in Form1099FormService.BuildCopyBHtml
from ChurchProfile.PayerEin (blank when null, matching prior behaviour).
Add payerEin field to ChurchProfileDto TS model (flows into
UpdateChurchProfileRequest via the existing Omit type) and a text input on
the Church Info tab of the church-profile settings page, mirroring the
Routing # field pattern. CSV left unchanged — adding a payer context line
would break the existing ExportFilingCsvAsync assertion (3 lines expected).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Chris Chen
a4ded78442