学年学期页面新增“设为当前”“归档”“撤销归档”，当前学期不能归档、删除或直接取消；已归档学期需先撤销才能重新设为当前。[BaseDataController.cs (line 286)](/E:/jiaowu/src/Jiaowu.Api/Controllers/BaseDataController.cs:286)

切换后，其他学期自动变为历史态；已归档学期进一步弱化。所有主要学期选择器统一默认当前，并显示“当前 / 历史 / 已归档”。[academicTerms.ts (line 1)](/E:/jiaowu/web/src/utils/academicTerms.ts:1)
桌面使用分层表格，390px 手机端改为独立学期卡片，操作不会再挤压表格。[BaseDataView.vue (line 211)](/E:/jiaowu/web/src/views/BaseDataView.vue:211)
归档定义为“历史显示状态”，不是成绩冻结：补考成绩仍可录入并回写，已发布成绩仍可走成绩更正审批。
已加入 SQLite 开发迁移、MySQL 正式迁移和切换/归档/撤销测试。[20260726143000_AcademicTermArchiving.cs (line 1)](/E:/jiaowu/src/Jiaowu.Api/Infrastructure/Persistence/Migrations/MySql/20260726143000_AcademicTermArchiving.cs:1)

src/Jiaowu.Api/Controllers/TimetableManagementController.cs

@@ -220,6 +220,7 @@ public sealed class FreeClassroomsController(AppDbContext db) : ControllerBase
         var terms = await db.AcademicTerms.AsNoTracking()
             .Where(x => x.IsEnabled)
             .OrderByDescending(x => x.IsCurrent)
+            .ThenBy(x => x.IsArchived)
             .ThenByDescending(x => x.StartDate)
             .Select(x => new
             {
@@ -228,6 +229,7 @@ public sealed class FreeClassroomsController(AppDbContext db) : ControllerBase
                 x.StartDate,
                 x.EndDate,
                 x.IsCurrent,
+                x.IsArchived,
                 HasPublishedTimetable = db.SchedulePlans.Any(plan =>
                     plan.AcademicTermId == x.Id &&
                     plan.Status == SchedulePlanStatus.Published)
@@ -235,6 +237,7 @@ public sealed class FreeClassroomsController(AppDbContext db) : ControllerBase
             .ToListAsync(cancellationToken);
         var selectedTermId = academicTermId
             ?? terms.FirstOrDefault(x => x.IsCurrent && x.HasPublishedTimetable)?.Id
+            ?? terms.FirstOrDefault(x => !x.IsArchived && x.HasPublishedTimetable)?.Id
             ?? terms.FirstOrDefault(x => x.HasPublishedTimetable)?.Id;
         var campuses = await db.Campuses.AsNoTracking()
             .Where(x => x.IsEnabled)