feat: store profile signature

packages/prisma/migrations/20230901083000_add_user_signature_column/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "User" ADD COLUMN     "signature" TEXT;

packages/prisma/schema.prisma

@@ -20,6 +20,7 @@ model User {
   emailVerified    DateTime?
   password         String?
   source           String?
+  signature        String?
   identityProvider IdentityProvider @default(DOCUMENSO)
   accounts         Account[]
   sessions         Session[]