课程库 Excel 导入导出已完成：

支持下载标准导入模板。
导出严格沿用当前关键词、学院、分类、课程性质和状态筛选。
以课程编码为唯一键：存在则更新，不存在则新增。
校验学院编码、课程分类、课程性质、学分学时及考核方式。
整批原子导入，任一行错误则全部不写入，并提示具体行号。
学院管理员仍只能维护本学院的专业课和实践课，无法借 Excel 越权。
界面入口沿用现有课程库工具栏样式。

tests/Jiaowu.Api.Tests/PersistenceTests.cs

@@ -111,6 +111,12 @@ public sealed class PersistenceTests : IAsyncLifetime
             Nature = CourseNature.MajorRequired,
             AssessmentMethod = AssessmentMethod.Examination
         };
+        var category = new CourseCategory
+        {
+            Code = "BASIC",
+            Name = "基础课程"
+        };
+        course.CourseCategoryId = category.Id;
         var teacher = new Teacher
         {
             TeacherNumber = "T2026001",
@@ -148,6 +154,7 @@ public sealed class PersistenceTests : IAsyncLifetime
             counselor,
             administrativeClass,
             teacher,
+            category,
             new Student
             {
                 StudentNumber = "202601001",
@@ -237,7 +244,10 @@ public sealed class PersistenceTests : IAsyncLifetime
         var savedClass = await _db.AdministrativeClasses
             .Include(x => x.CounselorUser)
             .SingleAsync();
-        var savedCourse = await _db.Courses.Include(x => x.College).SingleAsync();
+        var savedCourse = await _db.Courses
+            .Include(x => x.College)
+            .Include(x => x.CourseCategory)
+            .SingleAsync();
         var curriculumPlan = await _db.CurriculumPlans
             .Include(x => x.Modules)
             .ThenInclude(x => x.Courses)
@@ -255,6 +265,7 @@ public sealed class PersistenceTests : IAsyncLifetime
         Assert.Equal("计算机科学与技术", student.AdministrativeClass!.Major!.Name);
         Assert.Equal("陈老师", savedClass.CounselorUser!.DisplayName);
         Assert.Equal(4m, savedCourse.Credits);
+        Assert.Equal("基础课程", savedCourse.CourseCategory!.Name);
         Assert.Equal(savedCourse.TotalHours, savedCourse.LectureHours + savedCourse.PracticeHours);
         Assert.Single(curriculumPlan.Modules);
         Assert.Single(curriculumPlan.Modules.Single().Courses);