feat: finish bilingual session auth learning lab

web/WEB-INF/classes/com/demo/action/FileUploadAction.java

@@ -27,11 +27,11 @@ public class FileUploadAction extends ActionSupport {
         }
 
         if (fileCount == 0) {
-            addActionError("Select at least one file before submitting the demo.");
+            addActionError("请至少选择一个文件再提交。 / Select at least one file before submitting the demo.");
             return INPUT;
         }
 
-        summary = "This demo captures upload metadata only. It does not persist files to disk, which keeps the sample safe for classroom use.";
+        summary = "metadata-only";
         return SUCCESS;
     }