未选择相机的时候，增加请选择左侧相机的提示

src/views/cameras/preview/CameraPreview.vue

@@ -6,7 +6,8 @@
       </div>
       <div class="cameraSettingWrapper">
         <div class="cameraView">
-          <CameraViewSetting />
+          <CameraViewSetting v-if="cameraDetailStore.cameraId" />
+          <div class="cameraPlaceholder" v-else>请选择左侧相机</div>
         </div>
       </div>
     </div>
@@ -16,6 +17,8 @@
 <script lang="ts" setup>
   import CameraTree from './components/CameraTree/CameraTree.vue';
   import CameraViewSetting from './components/CameraViewSetting/CameraViewSetting.vue';
+  import useCameraDetailStore from './store/useCameraDetailStore';
+  const cameraDetailStore = useCameraDetailStore();
 </script>
 <style lang="scss" scoped>
   .cameraView {
@@ -50,4 +53,10 @@
     // height: 800px;
     // border: 1px solid #ccc;
   }
+
+  .cameraPlaceholder {
+    color: #ccc;
+    text-align: center;
+    margin-top: 100px;
+  }
 </style>