fix: 删除 teacher.ts 中重复的函数声明

删除了重复的 dashboard 相关函数:
- getTeacherDashboard
- getTeacherLessonTrend
- getTeacherCourseUsage
- getTeacherTodayLessons
- getTeacherRecommendedCourses
- getTeacherWeeklyStats

这些函数在文件中已经存在，之前的编辑造成了重复。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

reading-platform-frontend/src/api/teacher.ts

@@ -747,77 +747,3 @@ export const getMonthlyTaskStats = (months?: number) => {
   return api.teacherTaskControllerGetMonthlyStats(params) as any;
 };
 
-// ==================== 教师控制台 API ====================
-
-export interface DashboardStats {
-  classCount: number;
-  studentCount: number;
-  lessonCount: number;
-  courseCount: number;
-}
-
-export interface TodayLesson {
-  id: number;
-  classId: number;
-  className: string;
-  courseId: number;
-  courseName: string;
-  scheduledTime: string;
-  status: 'PENDING' | 'IN_PROGRESS' | 'COMPLETED' | 'CANCELLED';
-}
-
-export interface RecommendedCourse {
-  id: number;
-  name: string;
-  coverImagePath?: string;
-  gradeTags: string[];
-  domainTags: string[];
-  duration: number;
-  publishedAt: string;
-}
-
-export interface RecentActivity {
-  id: number;
-  type: 'lesson' | 'feedback' | 'task';
-  title: string;
-  description: string;
-  time: string;
-}
-
-export interface TeacherDashboardResponse {
-  stats: DashboardStats;
-  todayLessons: TodayLesson[];
-  recommendedCourses: RecommendedCourse[];
-  recentActivities: RecentActivity[];
-}
-
-// 获取教师控制台数据
-export function getTeacherDashboard(): Promise<TeacherDashboardResponse> {
-  return api.teacherCourseControllerGetDashboard() as any;
-}
-
-// 获取授课趋势
-export function getTeacherLessonTrend(months: number = 6): Promise<any[]> {
-  const params: TeacherCourseControllerGetLessonTrendParams = { months: String(months) };
-  return api.teacherCourseControllerGetLessonTrend(params) as any;
-}
-
-// 获取课程使用情况
-export function getTeacherCourseUsage(): Promise<any[]> {
-  return api.teacherCourseControllerGetCourseUsage() as any;
-}
-
-// 获取今日课程
-export function getTeacherTodayLessons(): Promise<TodayLesson[]> {
-  return api.teacherCourseControllerGetTodayLessons() as any;
-}
-
-// 获取推荐课程
-export function getTeacherRecommendedCourses(): Promise<RecommendedCourse[]> {
-  return api.teacherCourseControllerGetRecommend() as any;
-}
-
-// 获取周统计数据
-export function getTeacherWeeklyStats(): Promise<any> {
-  return api.teacherCourseControllerGetWeekly() as any;
-}