feat(products): port missing variant fields from henza and redesign variant modal

apps/api/prisma/migrations/20261025143000_variant_legacy_fields/migration.sql

@@ -0,0 +1,5 @@
+-- AlterTable: Add legacy variant fields (color, rialWage, details, description)
+ALTER TABLE "ProductVariant" ADD COLUMN IF NOT EXISTS "color" INTEGER;
+ALTER TABLE "ProductVariant" ADD COLUMN IF NOT EXISTS "rialWage" DECIMAL(18,0);
+ALTER TABLE "ProductVariant" ADD COLUMN IF NOT EXISTS "details" TEXT;
+ALTER TABLE "ProductVariant" ADD COLUMN IF NOT EXISTS "description" TEXT;

apps/api/prisma/schema.prisma

@@ -728,6 +728,15 @@ model ProductVariant {
   isPreOrder         Boolean @default(false)
   isActive           Boolean @default(true)
 
+  /// Legacy color enum: 0=سفید, 1=زرد, 2=شکلاتی, 3=رزگلد
+  color              Int?
+  /// Legacy rial_pay — fixed Rial making charge per variant.
+  rialWage           Decimal? @db.Decimal(18, 0)
+  /// Legacy details — short description for variant.
+  details            String?  @db.Text
+  /// Legacy description — full description for variant.
+  description        String?  @db.Text
+
   /// The gallery image shown for this variant, picked from its own product's
   /// images — never a re-uploaded copy. onDelete: SetNull because dropping an
   /// image must never cascade into the variant: OrderItem rows reference