feat(r3): complete order and payment flow

prisma/schema.prisma

@@ -56,8 +56,19 @@ model Product {
   name        String
   categoryId  String?
   price       Decimal         @db.Decimal(10, 2)
+  originalPrice Decimal?      @db.Decimal(10, 2)
+  leadTime     String          @default("7-10 个工作日")
+  subtitle     String?
+  tone         Int[]
+  tags         String[]
+  specs        Json?
+  mask         Json?
+  story        String?
+  scene        String?
+  iconImg      String?
   images      String[]
   description String?
+  sort        Int            @default(0)
   status      ProductStatus   @default(DRAFT)
   category    Category?       @relation(fields: [categoryId], references: [id])
   orderItems  OrderItem[]
@@ -127,6 +138,10 @@ model Order {
   status         OrderStatus  @default(PENDING)
   totalAmount    Decimal      @db.Decimal(10, 2)
   addressSnapshot Json
+  requestId      String?
+  paidAt         DateTime?
+  // 待付款订单的固定截止时刻；创建后 30 分钟不可再支付。
+  paymentExpiresAt DateTime?
   // 关联的设计清单（R4 下单后 WCD 派单据此读取 designData）
   designListId   String?
   user           User         @relation(fields: [userId], references: [id])
@@ -139,7 +154,9 @@ model Order {
 
   @@index([userId])
   @@index([status])
+  @@index([paymentExpiresAt])
   @@index([designListId])
+  @@unique([userId, requestId])
 }
 
 enum OrderStatus {
@@ -149,6 +166,7 @@ enum OrderStatus {
   SHIPPED
   COMPLETED
   CANCELLED
+  PAYMENT_EXPIRED
 }
 
 model OrderItem {