feat(payments): add Order & Escrow entities with CQRS commands, Prisma schema

- Add Order entity with lifecycle (pending → paid → completed/cancelled/refunded)
- Add Escrow entity with hold/release/dispute flow for secure transactions
- Add PlatformFee value object with tiered commission calculation
- Implement CQRS: CreateOrder, CancelOrder, HoldEscrow, ReleaseEscrow commands
- Add GetOrderStatus query handler
- Add OrdersController with REST endpoints and DTOs
- Add Prisma models for Order, Escrow, EscrowStatusHistory
- Add domain event classes for order and escrow state changes
- Add unit tests for Order, Escrow entities and PlatformFee VO
- Update PROJECT_TRACKER to Wave 14 status

Co-Authored-By: Claude Opus 4 (1M context) <noreply@anthropic.com>

prisma/schema.prisma

@@ -65,6 +65,8 @@ model User {
   refreshTokens     RefreshToken[]
   oauthAccounts     OAuthAccount[]
   buyerTransactions Transaction[]  @relation("BuyerTransactions")
+  buyerOrders       Order[]        @relation("BuyerOrders")
+  sellerOrders      Order[]        @relation("SellerOrders")
   mfaChallenges     MfaChallenge[]
 
   @@index([role])
@@ -275,6 +277,7 @@ model Listing {
 
   transactions Transaction[]
   inquiries    Inquiry[]
+  orders       Order[]
 
   // --- Single-column indexes ---
   @@index([status])
@@ -419,6 +422,7 @@ enum PaymentType {
   LISTING_FEE
   DEPOSIT
   FEATURED_LISTING
+  AUCTION_PAYMENT
 }
 
 model Payment {
@@ -427,6 +431,8 @@ model Payment {
   user           User            @relation(fields: [userId], references: [id], onDelete: Restrict)
   transactionId  String?
   transaction    Transaction?    @relation(fields: [transactionId], references: [id], onDelete: SetNull)
+  orderId        String?
+  order          Order?          @relation(fields: [orderId], references: [id], onDelete: SetNull)
   provider       PaymentProvider
   type           PaymentType
   amountVND      BigInt
@@ -440,6 +446,7 @@ model Payment {
   @@unique([userId, provider, idempotencyKey], name: "Payment_idempotency_unique")
   @@index([userId])
   @@index([transactionId])
+  @@index([orderId])
   @@index([status])
   @@index([providerTxId])
   @@index([createdAt])
@@ -448,6 +455,77 @@ model Payment {
   @@index([userId, type, createdAt(sort: Desc)])
 }
 
+// =============================================================================
+// ORDERS & ESCROW (Auction Settlement)
+// =============================================================================
+
+enum OrderStatus {
+  CREATED
+  PAYMENT_PENDING
+  PAYMENT_CONFIRMED
+  ESCROW_HELD
+  SHIPPED
+  DELIVERED
+  DISPUTE
+  ESCROW_RELEASED
+  COMPLETED
+  CANCELLED
+  REFUNDED
+}
+
+enum EscrowStatus {
+  PENDING
+  HELD
+  RELEASED
+  REFUNDED
+  DISPUTED
+}
+
+model Order {
+  id              String      @id @default(cuid())
+  buyerId         String
+  buyer           User        @relation("BuyerOrders", fields: [buyerId], references: [id], onDelete: Restrict)
+  sellerId        String
+  seller          User        @relation("SellerOrders", fields: [sellerId], references: [id], onDelete: Restrict)
+  listingId       String
+  listing         Listing     @relation(fields: [listingId], references: [id], onDelete: Restrict)
+  status          OrderStatus @default(CREATED)
+  amountVND       BigInt
+  platformFeeVND  BigInt
+  sellerPayoutVND BigInt
+  idempotencyKey  String?     @unique
+  metadata        Json?
+  createdAt       DateTime    @default(now())
+  updatedAt       DateTime    @updatedAt
+
+  payments Payment[]
+  escrow   Escrow?
+
+  @@index([buyerId])
+  @@index([sellerId])
+  @@index([listingId])
+  @@index([status])
+  @@index([createdAt(sort: Desc)])
+}
+
+model Escrow {
+  id            String       @id @default(cuid())
+  orderId       String       @unique
+  order         Order        @relation(fields: [orderId], references: [id], onDelete: Restrict)
+  amountVND     BigInt
+  feeVND        BigInt
+  status        EscrowStatus @default(PENDING)
+  heldAt        DateTime?
+  releasedAt    DateTime?
+  disputeReason String?      @db.Text
+  disputedAt    DateTime?
+  createdAt     DateTime     @default(now())
+  updatedAt     DateTime     @updatedAt
+
+  @@index([status])
+  @@index([orderId])
+}
+
 // =============================================================================
 // SUBSCRIPTIONS
 // =============================================================================