fix(teacher): 修复 CourseBasicInfo.vue 缺少 getThemeTagStyle 导入的错误

- 添加 getThemeTagStyle 函数从 @/utils/tagMaps 的导入
- 修复主题标签样式计算时函数未定义的错误

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

reading-platform-frontend/src/views/teacher/courses/components/content/CourseBasicInfo.vue

@@ -68,7 +68,7 @@ import { computed } from 'vue';
 import {
   InfoCircleOutlined, PictureOutlined, BarChartOutlined,
 } from '@ant-design/icons-vue';
-import { translateGradeTags } from '@/utils/tagMaps';
+import { translateGradeTags, getThemeTagStyle } from '@/utils/tagMaps';
 
 const props = defineProps<{
   course: any;