refactor(school,classes): 完成 school/grade/class 审计全量改进项

P0-1/P0-2: 删除 grade-management 死模块，年级 CRUD 统一由 school 模块负责

P0-3: classes/actions.ts 从 974 行拆分为 6 个职责文件 + barrel re-export

P0-5: 13 个页面 i18n 全量接入（grades/departments/academic-year/classes/insights）

P1-1: 角色硬编码改为 hasAdminScope/hasTeacherScope/hasStudentScope 基于 dataScope.type

P1-3: 新增 SchoolErrorBoundary + SchoolListSkeleton/SchoolCardSkeleton，4 个页面包裹 Error Boundary

P1-4: classes/types.ts 跨领域类型添加归属决策注释

P1-5: schools-view.tsx 拆分为组合模式（SchoolFormDialog + SchoolDeleteDialog + SchoolListToolbar）

P1-6: 新增 getSchoolsForUser/getGradesForUser 权限感知查询函数

P2-1: 抽取 useSchoolData hook，对话框状态管理与 UI 分离

同步更新架构图文档 004/005

src/modules/classes/actions-schedule.ts

@@ -0,0 +1,124 @@
+"use server"
+
+import { revalidatePath } from "next/cache"
+import { requirePermission, PermissionDeniedError } from "@/shared/lib/auth-guard"
+import { Permissions } from "@/shared/types/permissions"
+
+import type { ActionState } from "@/shared/types/action-state"
+import {
+  createClassScheduleItem,
+  updateClassScheduleItem,
+  deleteClassScheduleItem,
+} from "@/modules/scheduling/data-access-class-schedule"
+import {
+  CreateClassScheduleItemSchema,
+  UpdateClassScheduleItemSchema,
+  DeleteClassScheduleItemSchema,
+} from "./schema"
+import { toWeekday } from "./actions-shared"
+
+export async function createClassScheduleItemAction(
+  prevState: ActionState<string> | null,
+  formData: FormData
+): Promise<ActionState<string>> {
+  try {
+    await requirePermission(Permissions.CLASS_SCHEDULE)
+
+    const parsed = CreateClassScheduleItemSchema.safeParse({
+      classId: formData.get("classId"),
+      weekday: formData.get("weekday"),
+      course: formData.get("course"),
+      startTime: formData.get("startTime"),
+      endTime: formData.get("endTime"),
+      location: formData.get("location"),
+    })
+    if (!parsed.success) {
+      return { success: false, message: "Invalid schedule item data" }
+    }
+
+    const { classId, weekday, course, startTime, endTime, location } = parsed.data
+
+    try {
+      const id = await createClassScheduleItem({
+        classId,
+        weekday: toWeekday(weekday),
+        startTime,
+        endTime,
+        course,
+        location: location ?? null,
+      })
+      revalidatePath("/teacher/classes/schedule")
+      return { success: true, message: "Schedule item created successfully", data: id }
+    } catch (error) {
+      return { success: false, message: error instanceof Error ? error.message : "Failed to create schedule item" }
+    }
+  } catch (e) {
+    if (e instanceof PermissionDeniedError) return { success: false, message: e.message }
+    throw e
+  }
+}
+
+export async function updateClassScheduleItemAction(
+  scheduleId: string,
+  prevState: ActionState | null,
+  formData: FormData
+): Promise<ActionState> {
+  try {
+    await requirePermission(Permissions.CLASS_SCHEDULE)
+
+    const parsed = UpdateClassScheduleItemSchema.safeParse({
+      scheduleId,
+      classId: formData.get("classId"),
+      weekday: formData.get("weekday") || undefined,
+      course: formData.get("course"),
+      startTime: formData.get("startTime"),
+      endTime: formData.get("endTime"),
+      location: formData.get("location"),
+    })
+    if (!parsed.success) {
+      return { success: false, message: "Missing or invalid schedule id" }
+    }
+
+    const { scheduleId: validatedScheduleId, classId, weekday, course, startTime, endTime, location } = parsed.data
+
+    try {
+      await updateClassScheduleItem(validatedScheduleId, {
+        classId: classId ?? undefined,
+        weekday: typeof weekday === "number" ? toWeekday(weekday) : undefined,
+        startTime: startTime ?? undefined,
+        endTime: endTime ?? undefined,
+        course: course ?? undefined,
+        location: location ?? undefined,
+      })
+      revalidatePath("/teacher/classes/schedule")
+      return { success: true, message: "Schedule item updated successfully" }
+    } catch (error) {
+      return { success: false, message: error instanceof Error ? error.message : "Failed to update schedule item" }
+    }
+  } catch (e) {
+    if (e instanceof PermissionDeniedError) return { success: false, message: e.message }
+    throw e
+  }
+}
+
+export async function deleteClassScheduleItemAction(scheduleId: string): Promise<ActionState> {
+  try {
+    await requirePermission(Permissions.CLASS_SCHEDULE)
+
+    const parsed = DeleteClassScheduleItemSchema.safeParse({ scheduleId })
+    if (!parsed.success) {
+      return { success: false, message: "Missing schedule id" }
+    }
+
+    try {
+      await deleteClassScheduleItem(parsed.data.scheduleId)
+      revalidatePath("/teacher/classes/schedule")
+      return { success: true, message: "Schedule item deleted successfully" }
+    } catch (error) {
+      return { success: false, message: error instanceof Error ? error.message : "Failed to delete schedule item" }
+    }
+  } catch (e) {
+    if (e instanceof PermissionDeniedError) return { success: false, message: e.message }
+    throw e
+  }
+}