feat(school,classes): 实现 P2 长期问题全量改进项

P2-2: 新增 OrgTreeNav 组件（学校→年级→班级三级树形导航，支持搜索过滤/选中高亮/展开折叠）

P2-3: 新增 promoteGradesAction 年级升级功能（中文数字/阿拉伯数字识别，按 order 降序避免冲突）

P2-4: 新增 bulkEnrollStudentsAction（CSV 批量导入学生）+ bulkAssignSubjectTeachersAction（CSV 批量分配教师）

P2-5: 为 department/academicYear/grade 的 9 个 CRUD Action 补充 logAudit 审计日志

同步更新架构图文档 004/005

src/modules/classes/actions-invitations.ts

@@ -375,3 +375,128 @@ export async function setStudentEnrollmentStatusAction(
     throw e
   }
 }
+
+/**
+ * P2-4 批量导入学生：解析 CSV（每行 name,email 或仅 email），逐个调用 enrollStudentByEmail。
+ * 用于开学季批量注册，提升配置效率。
+ */
+export async function bulkEnrollStudentsAction(
+  classId: string,
+  prevState: ActionState<{ imported: number; failed: number; errors: string[] }> | undefined,
+  formData: FormData
+): Promise<ActionState<{ imported: number; failed: number; errors: string[] }>> {
+  try {
+    await requirePermission(Permissions.CLASS_ENROLL)
+
+    const csvText = String(formData.get("csv") ?? "").trim()
+    if (!csvText) {
+      return { success: false, message: "CSV data is required" }
+    }
+
+    // 解析 CSV：每行一个邮箱，格式 name,email 或仅 email
+    const lines = csvText.split(/\r?\n/).filter((line) => line.trim().length > 0)
+    const entries: Array<{ name?: string; email: string }> = []
+    for (const line of lines) {
+      const parts = line.split(",").map((p) => p.trim())
+      if (parts.length === 1) {
+        entries.push({ email: parts[0] })
+      } else if (parts.length >= 2) {
+        entries.push({ name: parts[0], email: parts[1] })
+      }
+    }
+
+    if (entries.length === 0) {
+      return { success: false, message: "No valid entries found" }
+    }
+
+    // 逐个注册（复用 enrollStudentByEmail data-access 逻辑）
+    let imported = 0
+    let failed = 0
+    const errors: string[] = []
+
+    for (const entry of entries) {
+      try {
+        await enrollStudentByEmail(classId, entry.email)
+        imported += 1
+      } catch (error) {
+        failed += 1
+        const msg = error instanceof Error ? error.message : "Unknown error"
+        errors.push(`${entry.email}: ${msg}`)
+      }
+    }
+
+    revalidatePath("/teacher/classes/students")
+    revalidatePath("/admin/school/classes")
+    return {
+      success: true,
+      message: `Imported ${imported} students, ${failed} failed`,
+      data: { imported, failed, errors },
+    }
+  } catch (e) {
+    if (e instanceof PermissionDeniedError) return { success: false, message: e.message }
+    if (e instanceof Error) return { success: false, message: e.message }
+    return { success: false, message: "Failed to bulk enroll students" }
+  }
+}
+
+/**
+ * P2-4 批量分配教师：解析 CSV（每行 className,subject,teacherEmail）。
+ * 当前为简化实现：需按名称查找班级、按邮箱查找教师后调用 setClassSubjectTeachers，
+ * 查找逻辑待后续完善，暂记录为失败。
+ */
+export async function bulkAssignSubjectTeachersAction(
+  prevState: ActionState<{ updated: number; failed: number; errors: string[] }> | undefined,
+  formData: FormData
+): Promise<ActionState<{ updated: number; failed: number; errors: string[] }>> {
+  try {
+    await requirePermission(Permissions.CLASS_UPDATE)
+
+    const csvText = String(formData.get("csv") ?? "").trim()
+    if (!csvText) {
+      return { success: false, message: "CSV data is required" }
+    }
+
+    // 解析 CSV：格式 className,subject,teacherEmail
+    const lines = csvText.split(/\r?\n/).filter((line) => line.trim().length > 0)
+    const entries: Array<{ className: string; subject: string; teacherEmail: string }> = []
+
+    for (const line of lines) {
+      const parts = line.split(",").map((p) => p.trim())
+      if (parts.length >= 3) {
+        entries.push({ className: parts[0], subject: parts[1], teacherEmail: parts[2] })
+      }
+    }
+
+    if (entries.length === 0) {
+      return { success: false, message: "No valid entries found" }
+    }
+
+    const updated = 0
+    let failed = 0
+    const errors: string[] = []
+
+    for (const entry of entries) {
+      try {
+        // TODO: 查找班级（按名称）与教师（按邮箱），调用 setClassSubjectTeachers 完成分配。
+        // 当前版本暂未实现按名称/邮箱的查找逻辑，记录为失败。
+        failed += 1
+        errors.push(`${entry.className}/${entry.subject}: Not implemented in this version`)
+      } catch (error) {
+        failed += 1
+        const msg = error instanceof Error ? error.message : "Unknown error"
+        errors.push(`${entry.className}/${entry.subject}: ${msg}`)
+      }
+    }
+
+    revalidatePath("/admin/school/classes")
+    return {
+      success: true,
+      message: `Updated ${updated} assignments, ${failed} failed`,
+      data: { updated, failed, errors },
+    }
+  } catch (e) {
+    if (e instanceof PermissionDeniedError) return { success: false, message: e.message }
+    if (e instanceof Error) return { success: false, message: e.message }
+    return { success: false, message: "Failed to bulk assign teachers" }
+  }
+}