设计图示（类图与时序图）

1. 类关系图（简化）
```mermaid
classDiagram
  class DeptController
  class EmployeeController
  class EmployeeKpiController
  class HireNumController
  class SalaryLevelController
  class LoginController
  class CaptchaController

  class IDeptService
  class IEmployeeService
  class IEmployeeKpiService
  class IHireNumService
  class ISalaryLevelService

  class Dept
  class Employee
  class EmployeeKpi
  class HireNum
  class SalaryLevel

  DeptController --> IDeptService
  EmployeeController --> IEmployeeService
  EmployeeKpiController --> IEmployeeKpiService
  HireNumController --> IHireNumService
  SalaryLevelController --> ISalaryLevelService

  IDeptService --> Dept
  IEmployeeService --> Employee
  IEmployeeKpiService --> EmployeeKpi
  IHireNumService --> HireNum
  ISalaryLevelService --> SalaryLevel
```

2. 登录时序图
```mermaid
sequenceDiagram
  participant U as User
  participant FE as Frontend(Vue)
  participant BE as Backend(Spring Boot)
  participant REDIS as Redis

  U->>FE: 打开登录页
  FE->>BE: GET /captchaImage
  BE->>REDIS: 保存(uuid -> code)
  BE-->>FE: uuid, img(Base64)
  U->>FE: 输入 username/password/code
  FE->>BE: POST /login {username,password,code,uuid}
  BE->>REDIS: 校验 code
  BE-->>FE: token
  FE->>FE: 保存 Admin-Token(Cookie)
```

3. 分页查询时序图
```mermaid
sequenceDiagram
  participant FE as Frontend
  participant CTRL as Controller
  participant SVC as Service
  participant DAO as Mapper/Repo

  FE->>CTRL: GET /<module>/list?query
  CTRL->>CTRL: startPage()
  CTRL->>SVC: select*List(query)
  SVC->>DAO: 查询
  DAO-->>SVC: 列表数据
  SVC-->>CTRL: 列表数据
  CTRL-->>FE: TableDataInfo
```