feat(portal-shell): lesson-plans 模块 6 页迁移（教师域 §9.1 B2）

§9.1 line 629 教师域 lesson-plans 行：
- /lesson-plans (列表) / /new (表单) / /library (教案库)
- /calendar (日历) / /heatmap (热力图) / /[planId]/edit (工作台)
契约：全 ❌ schema 无 → MSW 兜底 + @contract-pending

新增文件：
- src/lib/api/lesson-plans.ts (8 hooks)
- src/lib/api/operations/lesson-plans.graphql.ts (8 documents)
- src/features/teacher/lesson-plans/ (clients + transformations + tests)
- src/app/shell/teacher/lesson-plans/ (6 page.tsx + loading.tsx + error.tsx)

修改文件：
- src/mocks/graphql-data.ts (mock 数据 + handler cases)
- src/messages/{zh-CN,en}.json (lessonPlans i18n 命名空间)
- src/lib/api/{index,operations/index}.ts (导出 lesson-plans)
- src/shared/lib/route-permissions.ts (lesson-plans 路由权限声明)
- scripts/check-page-count.ts (baseline 31 → 37)

DoD 验收（§11.3 11 项）：
- typecheck 0 errors
- lint 0 errors
- vitest 405 tests passed (新增 48 tests)
- lint:tokens 0 errors
- check:pages 37 PASS
- route-permissions 已声明
- 三态（loading/error/empty）齐备
- @contract-pending + MSW 兜底
- i18n zh-CN + en 同步

关联：ARCHITECTURE.md §5.3 / §5.4 / §9.1 / §10 P2 / §11.3 / §11.4
契约工单：docs/architecture/issues/contracts/core-edu_contract.md

apps/portal-shell/src/shared/lib/route-permissions.ts

@@ -220,6 +220,18 @@ export const PREFIX_ROUTE_PERMISSIONS: Array<{
       anyOfPermissions: ["HOMEWORK_READ", "HOMEWORK_CREATE", "HOMEWORK_GRADE"],
     },
   },
+  // 教案管理（P2 迁移）
+  {
+    prefix: "/shell/teacher/lesson-plans/",
+    config: {
+      requiredRoles: ["teacher", "admin"],
+      anyOfPermissions: [
+        "LESSON_PLAN_READ",
+        "LESSON_PLAN_CREATE",
+        "LESSON_PLAN_UPDATE",
+      ],
+    },
+  },
   // 成绩录入
   {
     prefix: "/shell/teacher/grades/",