更新字节管理

backend-java/src/main/java/com/pharmacopoeia/controller/AdminKnowledgeController.java

@@ -415,9 +415,7 @@ public class AdminKnowledgeController {
             return s;
         }
         // Quick check: if the first 200 bytes look like garbled CJK, try GBK
-        for (int i = 0; i < header.length; i++) {
-            header[i] = bytes[i];
-        }
+        System.arraycopy(bytes, 0, header, 0, header.length);
         String utf8Head = new String(header, StandardCharsets.UTF_8);
         // If UTF-8 result contains replacement chars (�), it's likely GBK
         if (utf8Head.contains("�")) {