Step 0: Autonomous mode selected
Step 1: Scouted — 8 files mapped, 4 deps, 2 tests found
Step 2: Diagnosed — Root cause: OrderService.create()
        không validate address trước khi gọi Prisma.
        Prisma throw khi address.city = null (NOT NULL constraint).
        Evidence: stack trace → order.service.ts:67
Step 3: Moderate detected — Standard workflow
Step 4: Fixed — 2 files changed
        ├── src/modules/orders/dto/create-order.dto.ts
        │   → Thêm @IsNotEmpty() cho address fields
        └── src/modules/orders/orders.service.ts
            → Thêm validation trước Prisma call
Step 5: Verified + Prevented
        ├── Before: POST /api/orders {} → HTTP 500
        ├── After:  POST /api/orders {} → HTTP 422 + error details
        ├── Tests added: 3 (empty address, null city, valid order)
        └── Guard: class-validator DTO validation
Step 6: Complete — docs updated, ready to commit