Replace shared email commands with MediatR notifications (#280)

web/frontend/app/features/auth/auth.server.ts

@@ -21,9 +21,7 @@ interface LoginPayload {
     accessToken: string;
 }
 
-interface RegistrationPayload extends LoginPayload {
-    confirmationEmailSent: boolean;
-}
+type RegistrationPayload = LoginPayload;
 
 interface UpdateUsernamePayload {
     userAccountId: string;