feat: 登录页密码+验证码双模式 / 首页岗位优化 / 法律页面 / 后端接口完善

- 前端：登录页重构，支持密码登录、验证码登录、注册三种模式
- 前端：首页热门岗位添加「参考示例」标签，去虚构数据
- 前端：面试页顶部优化，岗位名+状态标签展示
- 前端：新增用户协议、隐私政策页面及免责声明
- 后端：新增 POST /api/user/register 注册接口
- 后端：新增 POST /api/user/set-password 设置密码接口
- 后端：修复 user.schema.ts unique 索引导致 null 冲突问题
- 后端：新增 payment-order.schema、positions.schema、site-config.schema
- 后端：package.json 新增 postbuild 脚本自动复制证书
- 管理后台：新增订单管理 Tab

backend/src/modules/user/user.service.ts

@@ -1,4 +1,5 @@
-import { Injectable, HttpException, HttpStatus } from '@nestjs/common'
+import * as bcrypt from 'bcrypt'
+import { Injectable, HttpException, HttpStatus } from '@nestjs/common'
 import { InjectModel } from '@nestjs/mongoose'
 import { Model } from 'mongoose'
 import { JwtService } from '@nestjs/jwt'
@@ -104,13 +105,59 @@ export class UserService {
 
     // 按邮箱查找或创建用户
     let user = await this.userModel.findOne({ email }).exec()
+    let isNew = false
     if (!user) {
+      isNew = true
       const nick = email.split('@')[0]
       user = await this.userModel.create({ email, nickname: nick, remaining: 3 })
     }
+    return { ...this.generateAuthResponse(user), isNew, hasPassword: !!user.password }
+  }
+
+  // 🔐 密码登录
+  async loginByPassword(email: string, password: string) {
+    const user = await this.userModel.findOne({ email }).exec()
+    if (!user) throw new HttpException('账号不存在', HttpStatus.NOT_FOUND)
+    if (!user.password) throw new HttpException('该账号未设置密码，请使用验证码登录', HttpStatus.UNAUTHORIZED)
+    const match = await bcrypt.compare(password, user.password)
+    if (!match) throw new HttpException('密码错误', HttpStatus.UNAUTHORIZED)
     return this.generateAuthResponse(user)
   }
 
+  // 📝 邮箱+密码注册
+  async registerWithPassword(email: string, password: string) {
+    if (!email || !email.includes('@')) {
+      throw new HttpException('请输入正确的邮箱地址', HttpStatus.BAD_REQUEST)
+    }
+    if (!password || password.length < 6) {
+      throw new HttpException('密码至少6位', HttpStatus.BAD_REQUEST)
+    }
+    const existing = await this.userModel.findOne({ email }).exec()
+    if (existing) {
+      if (existing.password) {
+        throw new HttpException('该邮箱已注册，请直接登录', HttpStatus.CONFLICT)
+      }
+      // 已有验证码注册的用户，补充设置密码
+      existing.password = await bcrypt.hash(password, 10)
+      await existing.save()
+      return this.generateAuthResponse(existing)
+    }
+    const nick = email.split('@')[0]
+    const hashed = await bcrypt.hash(password, 10)
+    const user = await this.userModel.create({ email, nickname: nick, password: hashed, remaining: 3 })
+    return this.generateAuthResponse(user)
+  }
+
+  // 🔑 已登录用户设置/修改密码
+  async setPassword(userId: string, password: string) {
+    if (!password || password.length < 6) {
+      throw new HttpException('密码至少6位', HttpStatus.BAD_REQUEST)
+    }
+    const hashed = await bcrypt.hash(password, 10)
+    await this.userModel.findByIdAndUpdate(userId, { password: hashed })
+    return { message: '密码设置成功' }
+  }
+
   async getInfo(userId: string) {
     const user = await this.userModel.findById(userId).exec()
     if (!user) throw new HttpException('用户不存在', HttpStatus.NOT_FOUND)