已继续完成“学籍异动”后端基础闭环：

学生可申请休学、复学或退学。
自动根据当前状态推导目标学籍状态。
同一学生不能同时提交多项在审申请。
强制执行辅导员 → 学院 → 校级三级审核。
驳回不会修改学生档案。
只有校级最终批准才更新学籍状态。
数据范围分别限制到本人、所带班级、所属学院或全校。
SQLite 增量升级和 MySQL 迁移已生成。
当前 28 项测试继续全部通过。

src/Jiaowu.Api/Infrastructure/Persistence/Migrations/MySql/20260724074551_StudentStatusChanges.cs

@@ -0,0 +1,57 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql
+{
+    /// <inheritdoc />
+    public partial class StudentStatusChanges : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "StudentStatusChanges",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "char(36)", nullable: false),
+                    StudentId = table.Column<Guid>(type: "char(36)", nullable: false),
+                    Type = table.Column<int>(type: "int", nullable: false),
+                    OriginalStatus = table.Column<int>(type: "int", nullable: false),
+                    TargetStatus = table.Column<int>(type: "int", nullable: false),
+                    Reason = table.Column<string>(type: "varchar(1000)", maxLength: 1000, nullable: false),
+                    State = table.Column<int>(type: "int", nullable: false),
+                    ReviewComment = table.Column<string>(type: "varchar(500)", maxLength: 500, nullable: true),
+                    SubmittedAt = table.Column<DateTime>(type: "datetime(6)", nullable: false),
+                    ReviewedAt = table.Column<DateTime>(type: "datetime(6)", nullable: true),
+                    ApprovedAt = table.Column<DateTime>(type: "datetime(6)", nullable: true),
+                    CreatedAt = table.Column<DateTime>(type: "datetime(6)", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "datetime(6)", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_StudentStatusChanges", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_StudentStatusChanges_Students_StudentId",
+                        column: x => x.StudentId,
+                        principalTable: "Students",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                })
+                .Annotation("MySQL:Charset", "utf8mb4");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_StudentStatusChanges_StudentId_State",
+                table: "StudentStatusChanges",
+                columns: new[] { "StudentId", "State" });
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "StudentStatusChanges");
+        }
+    }
+}

src/Jiaowu.Api/Infrastructure/Persistence/Migrations/MySql/AppDbContextModelSnapshot.cs

@@ -1054,6 +1054,58 @@ namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql
                     b.ToTable("Students");
                 });
 
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.StudentStatusChange", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("char(36)");
+
+                    b.Property<DateTime?>("ApprovedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<int>("OriginalStatus")
+                        .HasColumnType("int");
+
+                    b.Property<string>("Reason")
+                        .IsRequired()
+                        .HasMaxLength(1000)
+                        .HasColumnType("varchar(1000)");
+
+                    b.Property<string>("ReviewComment")
+                        .HasMaxLength(500)
+                        .HasColumnType("varchar(500)");
+
+                    b.Property<DateTime?>("ReviewedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<int>("State")
+                        .HasColumnType("int");
+
+                    b.Property<Guid>("StudentId")
+                        .HasColumnType("char(36)");
+
+                    b.Property<DateTime>("SubmittedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<int>("TargetStatus")
+                        .HasColumnType("int");
+
+                    b.Property<int>("Type")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("StudentId", "State");
+
+                    b.ToTable("StudentStatusChanges");
+                });
+
             modelBuilder.Entity("Jiaowu.Api.Domain.Academic.Teacher", b =>
                 {
                     b.Property<Guid>("Id")
@@ -1784,6 +1836,17 @@ namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql
                     b.Navigation("AdministrativeClass");
                 });
 
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.StudentStatusChange", b =>
+                {
+                    b.HasOne("Jiaowu.Api.Domain.Academic.Student", "Student")
+                        .WithMany()
+                        .HasForeignKey("StudentId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.Navigation("Student");
+                });
+
             modelBuilder.Entity("Jiaowu.Api.Domain.Academic.Teacher", b =>
                 {
                     b.HasOne("Jiaowu.Api.Domain.Academic.College", "College")