fix(Student视图): 将翻页快捷键从PageUp/PageDown改为ArrowUp/ArrowDown

修改键盘事件处理，使用更直观的方向键代替PageUp/PageDown来控制幻灯片导航

src/views/Student/index.vue

@@ -2279,7 +2279,7 @@ const handleKeydown = (e: KeyboardEvent) => {
         previousSlide()
       }
       break
-    case 'PageUp':
+    case 'ArrowUp':
       e.preventDefault()
       if (!isFollowModeActive.value || props.type == '1') {
         previousSlide()
@@ -2291,7 +2291,7 @@ const handleKeydown = (e: KeyboardEvent) => {
         nextSlide()
       }
       break
-    case 'PageDown':
+    case 'ArrowDown':
     case ' ':
       e.preventDefault()
       if (!isFollowModeActive.value || props.type == '1') {