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/Infrastructure/Persistence/Migrations/MySql/20260726143000_AcademicTermArchiving.cs

@@ -0,0 +1,48 @@
+using Jiaowu.Api.Infrastructure.Persistence;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql;
+
+[DbContext(typeof(AppDbContext))]
+[Migration("20260726143000_AcademicTermArchiving")]
+public partial class AcademicTermArchiving : Migration
+{
+    protected override void Up(MigrationBuilder migrationBuilder)
+    {
+        migrationBuilder.AddColumn<DateTime>(
+            name: "ArchivedAt",
+            table: "AcademicTerms",
+            type: "datetime(6)",
+            nullable: true);
+
+        migrationBuilder.AddColumn<bool>(
+            name: "IsArchived",
+            table: "AcademicTerms",
+            type: "tinyint(1)",
+            nullable: false,
+            defaultValue: false);
+
+        migrationBuilder.CreateIndex(
+            name: "IX_AcademicTerms_IsArchived",
+            table: "AcademicTerms",
+            column: "IsArchived");
+    }
+
+    protected override void Down(MigrationBuilder migrationBuilder)
+    {
+        migrationBuilder.DropIndex(
+            name: "IX_AcademicTerms_IsArchived",
+            table: "AcademicTerms");
+
+        migrationBuilder.DropColumn(
+            name: "ArchivedAt",
+            table: "AcademicTerms");
+
+        migrationBuilder.DropColumn(
+            name: "IsArchived",
+            table: "AcademicTerms");
+    }
+}