Add multi_value technical fields and FA category AI forms.

Support duplicatable free-text lists, always append سایر ویژگی‌ها on AI category forms, and fill leftover product specs into that field.

Co-authored-by: Cursor <cursoragent@cursor.com>

prisma/schema.prisma

@@ -1660,6 +1660,7 @@ enum TechnicalFieldType {
   textarea
   select
   multi_select
+  multi_value
 
   @@map("technical_field_type")
 }