feat: add student endpoint for listing course announcements

Add new AnnouncementsStudentController with GET endpoint for students to retrieve course announcements with pagination support. Endpoint requires JWT authentication and validates course enrollment.

Backend/src/controllers/announcementsController.ts

@@ -193,3 +193,36 @@ export class AnnouncementsController {
         });
     }
 }
+
+@Route('api/student/courses/{courseId}/announcements')
+@Tags('CoursesStudent')
+export class AnnouncementsStudentController {
+
+    /**
+     * ดึงรายการประกาศของคอร์ส (สำหรับนักเรียน)
+     * List announcements for a course (for students)
+     * @param courseId - รหัสคอร์ส / Course ID
+     * @param page - หน้าที่ต้องการ / Page number
+     * @param limit - จำนวนต่อหน้า / Items per page
+     */
+    @Get()
+    @Security('jwt')
+    @SuccessResponse('200', 'Announcements retrieved successfully')
+    @Response('401', 'Unauthorized')
+    @Response('403', 'Forbidden - Not enrolled in this course')
+    public async listAnnouncements(
+        @Request() request: any,
+        @Path() courseId: number,
+        @Query() page?: number,
+        @Query() limit?: number
+    ): Promise<ListAnnouncementResponse> {
+        const token = request.headers.authorization?.replace('Bearer ', '');
+        if (!token) throw new ValidationError('No token provided');
+        return await announcementsService.listAnnouncement({
+            token,
+            course_id: courseId,
+            page,
+            limit,
+        });
+    }
+}