feat(forecast): 添加自定义新增预测申报按钮

src/views/forecast/index.vue

@@ -20,6 +20,18 @@
       @row-save="rowSave"
       @row-cancel="rowCancel"
     >
+      <!-- 自定义新增按钮 -->
+      <template slot="menuLeft">
+        <el-button
+          type="primary"
+          size="small"
+          icon="el-icon-plus"
+          @click="rowAdd"
+        >
+          新增预测申报
+        </el-button>
+      </template>
+      
       <!-- 自定义审批状态显示 -->
       <template slot-scope="{row}" slot="approvalStatus">
         <el-tag