fix: 修正课程添加页面和班级选择器的标签显示

将addCourse3.vue中的班级标签改为年级类型标签
将GradeClassSelector.vue中的班级标签改为教学班级标签

src/components/common/GradeClassSelector.vue

@@ -2,7 +2,7 @@
   <div class="grade-class-selector">
     <div class="form-row">
       <div class="form-item required" style="width: 100%;">
-        <label class="form-label">{{ lang.ssClass }}</label>
+        <label class="form-label">{{ lang.ssTeachClass }}</label>
         <div class="class-selector">
           <div class="select-input" @click="toggleDropdown">
             <span class="input" :style="{'color': getSelectedClassName() ? '#303133' : '#c0c4cc'}">{{ getSelectedClassName() || lang.ssSelectClass }}</span>

src/components/pages/pptEasy/addCourse3.vue

@@ -822,7 +822,7 @@
                   />
                 </div>
                 <div class="form-item required">
-                  <label class="form-label">{{ lang.ssClass }}{{ lang.ssLabel }}</label>
+                  <label class="form-label">{{ lang.ssGradeType }}</label>
                   <selectTag
                     v-model="selectedGrade"
                     :options="gradeOptions"