refactor(ota_upgrade): 优化版本比较逻辑以支持升级和降级

改进版本比较方法，支持版本号长度不一致的情况，并允许检测升级和降级。同时将变量名从isUpdate改为hasUpdate以提高可读性，并添加flutter_screenutil的宽度单位

lib/modules/ota_upgrade/controllers/ota_upgrade_controller.dart

@@ -1,4 +1,5 @@
 import 'package:classic_bluetooth/classic_bluetooth.dart';
+import 'package:flutter_screenutil/flutter_screenutil.dart';
 import 'package:voitrans/data/models/appconfig_model.dart';
 import '/routes/app_routes.dart';
 import 'package:logger/web.dart';
@@ -214,10 +215,9 @@ class OtaUpgradeController extends GetxController {
       updatepackageaddress = product!.updatepackageaddress!;
 
       // 版本检查
-      bool isUpdate = _isNewVersionAvailable(product.version!);
+      bool hasUpdate = _isNewVersionAvailable(product.version!);
 
-
-      isUpdateAvailable.value = isUpdate;
+      isUpdateAvailable.value = hasUpdate;
     } catch (e) {
       // 统一错误处理
       errorMessage.value = e.toString();
@@ -238,22 +238,36 @@ class OtaUpgradeController extends GetxController {
     }
   }
 
-  // 版本比较方法优化
-  bool _isNewVersionAvailable(String latest) {
+  // 版本比较方法优化 - 支持升级和降级
+  bool _isNewVersionAvailable(String latestVersion) {
     try {
       List<int> currentParts = currentVersion.value
           .split('.')
           .map((e) => int.parse(e.trim()))
           .toList();
       List<int> latestParts =
-          latest.split('.').map((e) => int.parse(e.trim())).toList();
+          latestVersion.split('.').map((e) => int.parse(e.trim())).toList();
+
+      // 确保两个版本号长度一致，短的用0补齐
+      int maxLength = currentParts.length > latestParts.length
+          ? currentParts.length
+          : latestParts.length;
 
-      for (int i = 0; i < latestParts.length; i++) {
-        int current = (i < currentParts.length) ? currentParts[i] : 0;
-        if (latestParts[i] > current) return true;
-        if (latestParts[i] < current) return false;
+      while (currentParts.length < maxLength) {
+        currentParts.add(0);
       }
-      return false;
+      while (latestParts.length < maxLength) {
+        latestParts.add(0);
+      }
+
+      // 比较每一段，只要有不同就返回true（支持升级和降级）
+      for (int i = 0; i < maxLength; i++) {
+        if (latestParts[i] != currentParts[i]) {
+          return true; // 版本不同，允许更新（升级或降级）
+        }
+      }
+
+      return false; // 版本完全相同，无需更新
     } catch (e) {
       Logger().d('版本比较错误: $e');
       return false;
@@ -654,7 +668,7 @@ class OtaUpgradeController extends GetxController {
                   color: Colors.green[600],
                   size: 28,
                 ),
-                SizedBox(width: 12),
+                SizedBox(width: 12.w),
                 Text(
                   '升级成功',
                   style: TextStyle(