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/users/users.controller.ts

@@ -0,0 +1,18 @@
+import { Controller, Get, UseGuards } from '@nestjs/common';
+import { ApiBearerAuth, ApiOkResponse, ApiOperation, ApiTags } from '@nestjs/swagger';
+import { CurrentUser, JwtPayload } from '../common/decorators/current-user.decorator';
+import { UsersService } from './users.service';
+
+@ApiTags('用户')
+@ApiBearerAuth()
+@Controller('users')
+export class UsersController {
+  constructor(private readonly usersService: UsersService) {}
+
+  @Get('me')
+  @ApiOperation({ summary: '获取当前登录用户信息' })
+  @ApiOkResponse({ description: '当前用户' })
+  async getMe(@CurrentUser() user: JwtPayload) {
+    return this.usersService.findById(user.sub);
+  }
+}

src/users/users.module.ts

@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common';
+import { UsersController } from './users.controller';
+import { UsersService } from './users.service';
+
+@Module({
+  controllers: [UsersController],
+  providers: [UsersService],
+  exports: [UsersService],
+})
+export class UsersModule {}

src/users/users.service.ts

@@ -0,0 +1,25 @@
+import { Injectable } from '@nestjs/common';
+import { PrismaService } from '../prisma/prisma.service';
+
+@Injectable()
+export class UsersService {
+  constructor(private readonly prisma: PrismaService) {}
+
+  /** 按 openid 查询用户，不存在则创建（首次登录） */
+  async findOrCreateByOpenid(openid: string, unionid?: string) {
+    return this.prisma.user.upsert({
+      where: { openid },
+      update: unionid ? { unionid } : {},
+      create: { openid, unionid },
+    });
+  }
+
+  async findById(id: string) {
+    return this.prisma.user.findUnique({ where: { id } });
+  }
+
+  /** 更新昵称/头像/手机号（由小程序授权后回传） */
+  async updateProfile(id: string, data: { nickname?: string; avatar?: string; phone?: string }) {
+    return this.prisma.user.update({ where: { id }, data });
+  }
+}