继续优化了官方凭证的学生选择器：

管理员签发弹窗不再全量加载可见学生。
首屏与每次远程搜索最多返回 30 位匹配学生。
搜索范围仍严格遵循学院/校级数据权限。

src/Jiaowu.Api/Controllers/OfficialDocumentsController.cs

@@ -80,8 +80,13 @@ public sealed class OfficialDocumentsController(
     [Authorize(Roles = Managers)]
     public async Task<ActionResult> StudentOptions(
         string? keyword,
-        CancellationToken cancellationToken)
+        CancellationToken cancellationToken,
+        int page = 1,
+        int pageSize = 30)
     {
+        if (page < 1 || pageSize is < 1 or > 100)
+            return ValidationProblem("页码必须大于 0，且每页条数应在 1 至 100 之间。");
+
         var source = AccessibleStudents().AsNoTracking();
         if (!string.IsNullOrWhiteSpace(keyword))
         {
@@ -90,7 +95,10 @@ public sealed class OfficialDocumentsController(
                 x.StudentNumber.Contains(value) || x.Name.Contains(value));
         }
 
-        return Ok(await source.OrderBy(x => x.StudentNumber)
+        var total = await source.CountAsync(cancellationToken);
+        var items = await source.OrderBy(x => x.StudentNumber)
+            .Skip((page - 1) * pageSize)
+            .Take(pageSize)
             .Select(x => new
             {
                 x.Id,
@@ -101,7 +109,8 @@ public sealed class OfficialDocumentsController(
                 MajorName = x.AdministrativeClass.Major!.Name,
                 CollegeName = x.AdministrativeClass.Major.College!.Name
             })
-            .ToListAsync(cancellationToken));
+            .ToListAsync(cancellationToken);
+        return Ok(new PagedResult<object>(items, total, page, pageSize));
     }
 
     [HttpPost]