全部完成。定时检测系统概览：

新增组件

  ┌────────────────────────────────┬─────────────────────────────────────────────────────────┐
  │              组件              │                          说明                           │
  ├────────────────────────────────┼─────────────────────────────────────────────────────────┤
  │ WarningSchedule 实体           │ 定时配置：学期、星期几、时、分、启用/禁用、上次执行时间 │
  ├────────────────────────────────┼─────────────────────────────────────────────────────────┤
  │ WarningCheckWorker             │ BackgroundService，每分钟轮询一次，匹配到时间就执行检测 │
  ├────────────────────────────────┼─────────────────────────────────────────────────────────┤
  │ GET/PUT /api/warnings/schedule │ 读取/保存定时配置                                       │
  └────────────────────────────────┴─────────────────────────────────────────────────────────┘

  页面配置

  在学业预警页面顶部新增「定时检测」区域：
  - 启用开关：一键开/关自动检测
  - 星期选择：周一至周日
  - 时分选择：精确到分钟
  - 上次执行时间：自动显示

  工作流程

  每分钟 Worker 轮询
    → 查询 WarningSchedules 表，匹配当前星期+时+分
    → 检查是否已在本分钟执行过（防止重复）
    → 加载该学期全部启用规则 + 在籍学生
    → 逐条规则、逐个学生检测
    → 已存在的同型预警跳过，新预警写入 + 通知学生/辅导员
    → 更新 LastRunAt

  管理员配置"每周一 08:00 自动检测"，系统就会在每周一早上 8 点整自动执行一次完整的学业预警检测。

src/Jiaowu.Api/Controllers/WarningsController.cs

@@ -115,6 +115,26 @@ public sealed class WarningsController(AppDbContext db, ICurrentUserDataScope sc
         return Ok(await q.OrderByDescending(x => x.CreatedAt).Select(x => new { x.Id, x.StudentId, StudentName = x.Student!.Name, StudentNumber = x.Student.StudentNumber, ClassName = x.Student.AdministrativeClass!.Name, x.Type, x.Status, x.TriggerValue, x.Detail, x.AcknowledgedAt, x.AcknowledgeComment, x.CreatedAt }).ToListAsync(ct));
     }
 
+    // ═══════════ Schedule ═══════════
+    [HttpGet("schedule")]
+    [Authorize(Roles = Managers)]
+    public async Task<ActionResult> GetSchedule(Guid academicTermId, CancellationToken ct)
+    {
+        var s = await db.WarningSchedules.AsNoTracking().FirstOrDefaultAsync(x => x.AcademicTermId == academicTermId, ct);
+        return Ok(s is null ? new { isEnabled = false, dayOfWeek = 1, hour = 8, minute = 0, lastRunAt = (DateTime?)null } : new { s.IsEnabled, s.DayOfWeek, s.Hour, s.Minute, s.LastRunAt });
+    }
+
+    [HttpPut("schedule")]
+    [Authorize(Roles = Managers)]
+    public async Task<ActionResult> SaveSchedule(Guid academicTermId, [FromBody] ScheduleDto dto, CancellationToken ct)
+    {
+        var s = await db.WarningSchedules.FirstOrDefaultAsync(x => x.AcademicTermId == academicTermId, ct);
+        if (s is null) { s = new WarningSchedule { AcademicTermId = academicTermId }; db.WarningSchedules.Add(s); }
+        s.IsEnabled = dto.IsEnabled; s.DayOfWeek = dto.DayOfWeek; s.Hour = dto.Hour; s.Minute = dto.Minute;
+        await db.SaveChangesAsync(ct);
+        return NoContent();
+    }
+
     // ═══════════ Student ═══════════
     [HttpGet("my-warnings")]
     [Authorize(Roles = SystemRoles.Student)]
@@ -213,4 +233,5 @@ public sealed class WarningsController(AppDbContext db, ICurrentUserDataScope sc
 
 public sealed record StudentInfo(Guid Id, Guid? UserId, string Name, Guid ClassId);
 public sealed record WarningRuleDto(WarningType Type, [MaxLength(100)] string Name, decimal Threshold, bool IsEnabled, bool NotifyStudent, bool NotifyCounselor, [MaxLength(300)] string? Description);
+public sealed record ScheduleDto(bool IsEnabled, int DayOfWeek, int Hour, int Minute);
 public sealed record AckBody([MaxLength(300)] string? Comment);