fix(student page): 仅在有效用户ID下显示AI助手按钮和右侧面板

修复了无有效用户ID时错误显示AI助手按钮和右侧操作面板的问题，添加了props.userid != 'undefined'的判断条件

src/views/Student/index.vue

@@ -169,7 +169,7 @@
                 <IconStopwatchStart v-if="props.type == '1' && courseDetail.userid == props.userid && isFollowModeActive" class="tool-btn" v-tooltip="lang.ssTimer" @click="timerlVisible = !timerlVisible"  />
                 <IconWrite v-if="isFollowModeActive && props.type == '1' && courseDetail.userid == props.userid" class="tool-btn" v-tooltip="lang.ssPenTool" @click="writingBoardToolVisible = true"  />
                 <!-- <IconMagic v-if="isFollowModeActive && props.type == '1' && courseDetail.userid == props.userid" class="tool-btn" v-tooltip="lang.ssLaserPen" :class="{ 'active': laserPen }" @click="toggleLaserPen"  /> -->
-                <IconTips v-if="props.type == '1'" class="tool-btn" v-tooltip="lang.ssAiHelper" :class="{ 'active': !workPanelCollapsed }" @click="workPanelCollapsed = !workPanelCollapsed"  />
+                <IconTips v-if="props.type == '1' && props.userid != 'undefined'" class="tool-btn" v-tooltip="lang.ssAiHelper" :class="{ 'active': !workPanelCollapsed }" @click="workPanelCollapsed = !workPanelCollapsed"  />
                 <IconFullScreenOne class="tool-btn" v-tooltip="lang.ssOpenFull" @click="enterFullscreen" />
               </div>
           </div>
@@ -240,7 +240,7 @@
         </div>
       </div>
     </div>
-    <div class="layout-content-right" v-show="type == '1'" :class="{ collapsed: workPanelCollapsed }">
+    <div class="layout-content-right" v-show="type == '1' && props.userid != 'undefined'" :class="{ collapsed: workPanelCollapsed }">
       <div class="thumbnails">
         <div class="viewer-header right-panel-header">
           <button class="collapse-btn" @click="workPanelCollapsed = !workPanelCollapsed" :title="workPanelCollapsed ? lang.ssExpand : lang.ssCollapse" v-if="rightPanelMode != ''" style="left: 8px;">