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。

src/Jiaowu.Api/Infrastructure/Persistence/DatabaseInitializer.cs

@@ -28,6 +28,7 @@ public sealed class DatabaseInitializer(
 
         await SeedRolesAsync();
         await SeedAdministratorAsync();
+        await SeedCourseCategoriesAsync();
 
         if (environment.IsDevelopment())
         {
@@ -108,6 +109,55 @@ public sealed class DatabaseInitializer(
         }
     }
 
+    private async Task SeedCourseCategoriesAsync()
+    {
+        var defaults = new[]
+        {
+            ("BASIC", "基础课程", 10),
+            ("MORAL", "德育课程", 20),
+            ("AESTHETIC", "美育课程", 30),
+            ("LABOR", "劳动教育", 40),
+            ("INNOVATION", "创新创业", 50),
+            ("ENGLISH", "大学英语", 60),
+            ("SPORTS", "大学体育", 70),
+            ("MILITARY", "国防教育", 80),
+            ("MAJOR", "专业教育", 90),
+            ("PRACTICE", "实践教学", 100)
+        };
+        var existingCodes = (await db.CourseCategories
+            .Select(x => x.Code)
+            .ToListAsync())
+            .ToHashSet(StringComparer.OrdinalIgnoreCase);
+        foreach (var (code, name, sortOrder) in defaults)
+        {
+            if (existingCodes.Contains(code)) continue;
+            db.CourseCategories.Add(new CourseCategory
+            {
+                Code = code,
+                Name = name,
+                SortOrder = sortOrder
+            });
+        }
+        await db.SaveChangesAsync();
+
+        var categories = await db.CourseCategories
+            .ToDictionaryAsync(x => x.Code, StringComparer.OrdinalIgnoreCase);
+        var uncategorizedCourses = await db.Courses
+            .Where(x => x.CourseCategoryId == null)
+            .ToListAsync();
+        foreach (var course in uncategorizedCourses)
+        {
+            var categoryCode = course.Nature switch
+            {
+                CourseNature.Practice => "PRACTICE",
+                CourseNature.MajorRequired or CourseNature.MajorElective => "MAJOR",
+                _ => "BASIC"
+            };
+            course.CourseCategoryId = categories[categoryCode].Id;
+        }
+        await db.SaveChangesAsync();
+    }
+
     private async Task SeedDevelopmentDataAsync()
     {
         if (!await db.Campuses.AnyAsync())
@@ -242,6 +292,9 @@ public sealed class DatabaseInitializer(
                 });
         }
 
+        var courseCategories = await db.CourseCategories
+            .ToDictionaryAsync(x => x.Code, StringComparer.OrdinalIgnoreCase);
+
         if (!await db.Courses.AnyAsync())
         {
             db.Courses.AddRange(
@@ -251,6 +304,7 @@ public sealed class DatabaseInitializer(
                     Name = "程序设计基础",
                     EnglishName = "Fundamentals of Programming",
                     CollegeId = computerCollege.Id,
+                    CourseCategoryId = courseCategories["BASIC"].Id,
                     Credits = 4,
                     TotalHours = 64,
                     LectureHours = 40,
@@ -265,6 +319,7 @@ public sealed class DatabaseInitializer(
                     Name = "数据结构",
                     EnglishName = "Data Structures",
                     CollegeId = computerCollege.Id,
+                    CourseCategoryId = courseCategories["BASIC"].Id,
                     Credits = 3.5m,
                     TotalHours = 56,
                     LectureHours = 40,
@@ -278,6 +333,7 @@ public sealed class DatabaseInitializer(
                     Name = "软件工程实践",
                     EnglishName = "Software Engineering Practice",
                     CollegeId = computerCollege.Id,
+                    CourseCategoryId = courseCategories["PRACTICE"].Id,
                     Credits = 2,
                     TotalHours = 48,
                     LectureHours = 8,
@@ -286,7 +342,6 @@ public sealed class DatabaseInitializer(
                     AssessmentMethod = AssessmentMethod.Assessment
                 });
         }
-
         await db.SaveChangesAsync();
 
         if (!await db.CurriculumPlans.AnyAsync())