feat: 初始化微信小程序后端骨架

- NestJS + TypeScript + Prisma + PostgreSQL 工程骨架
- 微信登录安全流程：服务端 code2Session 换 openid 后签发 JWT，
  session_key 缓存于 Redis，不信任前端 openid
- 统一响应/异常处理、JWT 全局鉴权（@Public 豁免）、Swagger 文档
- Prisma 全量核心 schema（用户/分类/商品/设计清单/地址/订单/支付/上传/定制任务）+ seed
- 业务模块空壳（商品/分类/设计清单/地址/订单/支付/上传/BullMQ 队列）
- Docker 多阶段镜像 + 本地/生产 docker-compose
- docs：密钥获取指南、COS SDK 移除记录

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/orders/orders.service.ts

@@ -0,0 +1,58 @@
+import { Injectable } from '@nestjs/common';
+import { Prisma } from '@prisma/client';
+import { PrismaService } from '../prisma/prisma.service';
+import { CreateOrderDto } from './dto/create-order.dto';
+
+// 订单号生成：日期 + 随机后缀（无 Math.random 依赖要求仅限 workflow 脚本，普通运行时可用）
+function generateOrderNo(): string {
+  const now = new Date();
+  const ymd =
+    now.getUTCFullYear().toString() +
+    String(now.getUTCMonth() + 1).padStart(2, '0') +
+    String(now.getUTCDate()).padStart(2, '0');
+  const rand = Math.random().toString(36).slice(2, 8).toUpperCase();
+  return `${ymd}${rand}`;
+}
+
+@Injectable()
+export class OrdersService {
+  constructor(private readonly prisma: PrismaService) {}
+
+  async listByUser(userId: string) {
+    return this.prisma.order.findMany({
+      where: { userId },
+      include: { items: true, payment: true },
+      orderBy: { createdAt: 'desc' },
+    });
+  }
+
+  async findOne(id: string) {
+    // TODO: 权限校验（仅本人）
+    return this.prisma.order.findUnique({
+      where: { id },
+      include: { items: true, payment: true },
+    });
+  }
+
+  async create(userId: string, dto: CreateOrderDto) {
+    // TODO: 商品库存/价格校验、事务原子性、金额防篡改（服务端重算 totalAmount）
+    const totalAmount = dto.items.reduce((sum, it) => sum + it.price * it.quantity, 0);
+
+    const data: Prisma.OrderCreateInput = {
+      orderNo: generateOrderNo(),
+      user: { connect: { id: userId } },
+      totalAmount,
+      addressSnapshot: dto.addressSnapshot as Prisma.InputJsonValue,
+      items: {
+        create: dto.items.map((it) => ({
+          productId: it.productId,
+          name: it.name,
+          price: it.price,
+          quantity: it.quantity,
+        })),
+      },
+    };
+
+    return this.prisma.order.create({ data, include: { items: true } });
+  }
+}