已修改完成，同时解决了“考生名单都是 0 人”的根因。

考生范围统一为“行政班关联学生 + 已选课学生”，并自动去重；考场分配、人数显示、冲突检测、学生考试安排均使用同一口径。[TeachingTaskRosterQuery.cs (line 40)](E:/jiaowu/src/Jiaowu.Api/Infrastructure/Teaching/TeachingTaskRosterQuery.cs:40)
新增考场签名单 Excel 导出接口。[ExamsController.cs (line 568)](E:/jiaowu/src/Jiaowu.Api/Controllers/ExamsController.cs:568)
考试计划页面新增“导出考场签名单”按钮。[ExamsView.vue (line 255)](E:/jiaowu/web/src/views/ExamsView.vue:255)
工作簿包含“考场汇总”以及每个考试场次独立的 A4 签到表，字段包括座位号、学号、姓名、行政班、考生签名和备注。[ExamSignInWorkbookExporter.cs (line 12)](E:/jiaowu/src/Jiaowu.Api/Infrastructure/Exams/ExamSignInWorkbookExporter.cs:12)
未分配考场或监考教师时，也能导出并显示“待分配”。

tests/Jiaowu.Api.Tests/MySqlMigrationTests.cs

@@ -119,15 +119,28 @@ public sealed class MySqlMigrationTests
     public void MySql_teaching_task_roster_query_is_translatable()
     {
         using var db = new AppDbContext(CreateMySqlOptions());
+        var studentId =
+            Guid.Parse("22222222-2222-2222-2222-222222222222");
 
         var sql = TeachingTaskRosterQuery
             .ForTask(
                 db,
                 Guid.Parse("11111111-1111-1111-1111-111111111111"))
             .ToQueryString();
+        var taskIdsSql = TeachingTaskRosterQuery
+            .TaskIdsForStudent(db, studentId)
+            .ToQueryString();
 
         Assert.Contains("TeachingTaskClasses", sql, StringComparison.OrdinalIgnoreCase);
         Assert.Contains("CourseEnrollments", sql, StringComparison.OrdinalIgnoreCase);
+        Assert.Contains(
+            "TeachingTaskClasses",
+            taskIdsSql,
+            StringComparison.OrdinalIgnoreCase);
+        Assert.Contains(
+            "CourseEnrollments",
+            taskIdsSql,
+            StringComparison.OrdinalIgnoreCase);
     }
 
     [Fact]