refactor(backend): update employees endpoint and service

- endpoints/employees.py: update employees API endpoint
- services/employee.py: update employee service

server/src/app/api/v1/endpoints/employees.py

@@ -125,3 +125,22 @@ def disable_employee(employee_id: str, db: DbSession) -> EmployeeRead:
         return EmployeeService(db).disable_employee(employee_id)
     except LookupError as exc:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail=str(exc)) from exc
+
+
+@router.post(
+    "/{employee_id}/enable",
+    response_model=EmployeeRead,
+    summary="启用员工",
+    description="将停用员工恢复为在职状态，使其可以重新登录系统。",
+    responses={
+        status.HTTP_404_NOT_FOUND: {
+            "model": ErrorResponse,
+            "description": "员工不存在。",
+        }
+    },
+)
+def enable_employee(employee_id: str, db: DbSession) -> EmployeeRead:
+    try:
+        return EmployeeService(db).enable_employee(employee_id)
+    except LookupError as exc:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail=str(exc)) from exc

server/src/app/services/employee.py

@@ -333,6 +333,27 @@ class EmployeeService:
         logger.info("Disabled employee id=%s no=%s", employee.id, employee.employee_no)
         return self._serialize_employee(hydrated or saved)
 
+    def enable_employee(self, employee_id: str) -> EmployeeRead:
+        self.ensure_directory_ready()
+
+        employee = self.repository.get(employee_id)
+        if employee is None:
+            raise LookupError("Employee not found")
+
+        if employee.employment_status != "停用":
+            return self._serialize_employee(employee)
+
+        now = datetime.now()
+        employee.employment_status = "在职"
+        employee.sync_state = "已同步"
+        employee.last_sync_at = now
+        self._append_change_log(employee, action="启用员工账号", occurred_at=now)
+
+        saved = self.repository.save(employee)
+        hydrated = self.repository.get(saved.id)
+        logger.info("Enabled employee id=%s no=%s", employee.id, employee.employee_no)
+        return self._serialize_employee(hydrated or saved)
+
     def _seed_roles(self) -> None:
         existing_by_code = {role.role_code: role for role in self.repository.list_roles()}