完善考勤：支持未签到学员人工登记缺勤

名册中无任何打卡记录的已报到学员此前只能"先签到再改成缺勤"，会留下伪造的签到事实。

- 新增 POST /train/attendance/mark-absence，权限 train:attendance:edit，带操作日志
- 写入 attendance_status=0、sign_in_time 与 sign_out_time 保持 NULL、manual_flag=1，
  缺勤原因必填，绝不伪造签到时间
- 前置条件全部 fail closed：课次已开始、与课次同属一个开班计划、
  参训状态必须恰好为已报到；请假不得被自动改写为缺勤
- 已有考勤记录时拒绝新建并引导改用调整考勤记录，
  并发命中唯一索引转为同一业务错误，不泄露数据库异常
- 名册新增 canMarkAbsence，前端直接采用后端判定，登记后可继续调整考勤记录
- 未改动出勤率统计口径与 Analytics 业务策略

Co-authored-by: Cursor <cursoragent@cursor.com>

RuoYi-Vue/ruoyi-admin/src/main/java/com/ruoyi/web/controller/train/AttendanceController.java

@@ -17,6 +17,7 @@ import com.ruoyi.common.enums.BusinessType;
 import com.ruoyi.common.utils.SecurityUtils;
 import com.ruoyi.train.domain.TrainStudentCheckin;
 import com.ruoyi.train.domain.dto.AttendanceAdjustDTO;
+import com.ruoyi.train.domain.dto.AttendanceMarkAbsenceDTO;
 import com.ruoyi.train.domain.dto.AttendanceSignInDTO;
 import com.ruoyi.train.domain.dto.AttendanceSignOutDTO;
 import com.ruoyi.train.service.AttendanceAppService;
@@ -72,6 +73,18 @@ public class AttendanceController extends BaseController
         return success();
     }
 
+    /**
+     * 课次缺勤登记 (对名册中无任何打卡事实的学员直接登记缺勤)。
+     */
+    @PreAuthorize("@ss.hasPermi('train:attendance:edit')")
+    @Log(title = "课次缺勤登记", businessType = BusinessType.INSERT)
+    @PostMapping("/mark-absence")
+    public AjaxResult markAbsence(@Validated @RequestBody AttendanceMarkAbsenceDTO dto)
+    {
+        TrainStudentCheckin checkin = attendanceAppService.markAbsence(dto, SecurityUtils.getUsername());
+        return success(checkin);
+    }
+
     /**
      * 查询课次学员考勤名册 (纯只读，供培训管理员点名签到)。
      */

RuoYi-Vue/ruoyi-admin/src/test/java/com/ruoyi/web/controller/train/AttendanceAndReportApiControllerContractTest.java

@@ -9,7 +9,10 @@ import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.PutMapping;
+import com.ruoyi.common.annotation.Log;
+import com.ruoyi.common.enums.BusinessType;
 import com.ruoyi.train.domain.dto.AttendanceAdjustDTO;
+import com.ruoyi.train.domain.dto.AttendanceMarkAbsenceDTO;
 import com.ruoyi.train.domain.dto.AttendanceSignInDTO;
 import com.ruoyi.train.domain.dto.AttendanceSignOutDTO;
 import com.ruoyi.train.domain.dto.ReportConfirmDTO;
@@ -58,7 +61,19 @@ public class AttendanceAndReportApiControllerContractTest
         assertEquals("/{checkinId}", putAdjust.value()[0]);
         assertEquals("@ss.hasPermi('train:attendance:edit')", adjust.getAnnotation(PreAuthorize.class).value());
 
-        // 4. 课次学员考勤名册 (纯只读，供管理员点名签到)
+        // 4. 课次缺勤登记 (对无任何打卡事实的学员直接登记缺勤)
+        Method markAbsence = AttendanceController.class.getMethod("markAbsence", AttendanceMarkAbsenceDTO.class);
+        assertNotNull(markAbsence);
+        PostMapping postMarkAbsence = markAbsence.getAnnotation(PostMapping.class);
+        assertNotNull(postMarkAbsence);
+        assertEquals("/mark-absence", postMarkAbsence.value()[0]);
+        assertEquals("@ss.hasPermi('train:attendance:edit')", markAbsence.getAnnotation(PreAuthorize.class).value());
+        Log markAbsenceLog = markAbsence.getAnnotation(Log.class);
+        assertNotNull(markAbsenceLog);
+        assertEquals("课次缺勤登记", markAbsenceLog.title());
+        assertEquals(BusinessType.INSERT, markAbsenceLog.businessType());
+
+        // 5. 课次学员考勤名册 (纯只读，供管理员点名签到)
         Method getRoster = AttendanceController.class.getMethod("getLessonRoster", Long.class);
         assertNotNull(getRoster);
         GetMapping getRosterAnnotation = getRoster.getAnnotation(GetMapping.class);