feat(plan): 添加生成学案功能及界面支持

- 新增 AddLessonPlanReqVO 数据模型用于生成学案请求参数封装
- 新增 LessonPlanController 提供生成学案的后端接口，支持异步任务执行
- 新增 LessonPlanDialog 组件，实现前端学案生成弹窗及交互逻辑
- 在班级页面添加生成学案按钮，支持单个学生选择后调用弹窗
- 添加 plan.js 接口调用封装，调用后端生成学案接口
- 完成前后端联动，实现生成学案操作的完整流程和提示信息

enlish-vue/src/pages/class.vue

@@ -49,6 +49,10 @@
                                 @click="showGenerateDialog = true">
                                 生成试题
                             </el-button>
+                            <el-button type="warning" :disabled="selectedStudentIds.length !== 1"
+                                @click="showLessonPlanDialog = true">
+                                生成学案
+                            </el-button>
                         </div>
                         <el-table ref="studentTableRef" :data="students" border class="w-full"
                             v-loading="studentLoading" @selection-change="onStudentSelectionChange">
@@ -79,6 +83,10 @@
                             :default-grade-id="selectedGradeId"
                             @success="fetchStudents"
                         />
+                        <LessonPlanDialog
+                            v-model="showLessonPlanDialog"
+                            :student-id="selectedStudentIds[0]"
+                        />
                     </div>
 
                     <div class="bg-white dark:bg-gray-800 rounded-lg shadow p-6" v-loading="gradeLoading">
@@ -156,6 +164,7 @@ import ExamGenerateDialog from '@/layouts/components/ExamGenerateDialog.vue'
 import AddClassDialog from '@/layouts/components/AddClassDialog.vue'
 import AddGradeDialog from '@/layouts/components/AddGradeDialog.vue'
 import AddStudentDialog from '@/layouts/components/AddStudentDialog.vue'
+import LessonPlanDialog from '@/layouts/components/LessonPlanDialog.vue'
 import { getUnitList, deleteUnit } from '@/api/unit'
 import AddUnitDialog from '@/layouts/components/AddUnitDialog.vue'
 
@@ -189,6 +198,7 @@ const studentTableRef = ref(null)
 const selectedStudentIds = ref([])
 const showGenerateDialog = ref(false)
 const showAddStudentDialog = ref(false)
+const showLessonPlanDialog = ref(false)
 
 const units = ref([])
 const unitPageNo = ref(1)