Phase 1A scaffold. The form posts to POST /api/v1/SendGrid/send-callback-email— wiring + validation in Phase 1C (port of `Pages/FrontEnd/ContactUs.razor`).
Phase 1A scaffold. The form posts to POST /api/v1/SendGrid/send-callback-email— wiring + validation in Phase 1C (port of `Pages/FrontEnd/ContactUs.razor`).