feat: add granular signup disable flags (#2765)

apps/remix/app/routes/_recipient+/sign.$token+/complete.tsx

@@ -1,6 +1,7 @@
 import signingCelebration from '@documenso/assets/images/signing-celebration.png';
 import { getOptionalSession } from '@documenso/auth/server/lib/utils/get-session';
 import { useOptionalSession } from '@documenso/lib/client-only/providers/session';
+import { isSignupEnabledForProvider } from '@documenso/lib/constants/auth';
 import { getDocumentAndSenderByToken } from '@documenso/lib/server-only/document/get-document-by-token';
 import { isRecipientAuthorized } from '@documenso/lib/server-only/document/is-recipient-authorized';
 import { getFieldsForToken } from '@documenso/lib/server-only/field/get-fields-for-token';
@@ -8,7 +9,6 @@ import { getRecipientByToken } from '@documenso/lib/server-only/recipient/get-re
 import { getRecipientSignatures } from '@documenso/lib/server-only/recipient/get-recipient-signatures';
 import { getUserByEmail } from '@documenso/lib/server-only/user/get-user-by-email';
 import { isDocumentCompleted } from '@documenso/lib/utils/document';
-import { env } from '@documenso/lib/utils/env';
 import { trpc } from '@documenso/trpc/react';
 import { DocumentShareButton } from '@documenso/ui/components/document/document-share-button';
 import { SigningCard3D } from '@documenso/ui/components/signing-card';
@@ -77,7 +77,7 @@ export async function loader({ params, request }: Route.LoaderArgs) {
   const recipientName =
     recipient.name || fields.find((field) => field.type === FieldType.NAME)?.customText || recipient.email;
 
-  const canSignUp = !isExistingUser && env('NEXT_PUBLIC_DISABLE_SIGNUP') !== 'true';
+  const canSignUp = !isExistingUser && isSignupEnabledForProvider('email');
 
   const canRedirectToFolder = user && document.userId === user.id && document.folderId && document.team?.url;