refactor(storage): update Backend.Put to return PutResult and encapsulate bucket mapping

- Update Backend.Put method signature in storage.go to return (PutResult, error).
- Adjust all backend implementations (local, oss, s3, webdav) to return a PutResult enclosing Key and Bucket.
- Refactor storeUploadFile in upload routers.go to extract key/bucket from PutResult, eliminating manual config bucket lookups.
- Remove the unused cfgBucket helper from storage_ops.go.
- Adjust storage_migration_task.go and tests to accommodate the updated method signature.

internal/apps/upload/routers.go

@@ -404,22 +404,13 @@ func storeUploadFile(ctx context.Context, subPath string, size int64, mimeType s
 		logger.ErrorF(ctx, "初始化活动存储失败: %v", err)
 		return "", "", ErrSaveFileFailed
 	}
-	storedPath, err := backend.Put(ctx, subPath, bytes.NewReader(buf.Bytes()), size, mimeType)
+	result, err := backend.Put(ctx, subPath, bytes.NewReader(buf.Bytes()), size, mimeType)
 	if err != nil {
 		logger.ErrorF(ctx, "写入 %s 存储失败: %v", driver, err)
 		return "", "", ErrSaveFileFailed
 	}
-	switch driver {
-	case storage.DriverS3:
-		meta.Bucket = cfgBucket(ctx, driver)
-	case storage.DriverR2:
-		meta.Bucket = cfgBucket(ctx, driver)
-	case storage.DriverMinIO:
-		meta.Bucket = cfgBucket(ctx, driver)
-	case storage.DriverOSS:
-		meta.Bucket = cfgBucket(ctx, driver)
-	}
-	return string(driver), storedPath, ""
+	meta.Bucket = result.Bucket
+	return string(driver), result.Key, ""
 }
 
 // isImageExtension 判断文件扩展名是否属于常见图片格式

internal/apps/upload/storage_migration_task.go

@@ -287,7 +287,7 @@ func migrateObjects(
 					}
 					return fmt.Errorf("open source object %q: %w", obj.FilePath, err)
 				}
-				targetPath, putErr := targetBackend.Put(ctx, obj.FilePath, source.Body, obj.FileSize, obj.MimeType)
+				targetResult, putErr := targetBackend.Put(ctx, obj.FilePath, source.Body, obj.FileSize, obj.MimeType)
 				closeErr := source.Body.Close()
 				if putErr != nil {
 					return fmt.Errorf("copy object %q: %w", obj.FilePath, putErr)
@@ -298,7 +298,7 @@ func migrateObjects(
 
 				// Data integrity check (SHA-256 hash verification)
 				if len(obj.Hash) == sha256HexLength {
-					targetObj, getErr := targetBackend.Get(ctx, targetPath)
+					targetObj, getErr := targetBackend.Get(ctx, targetResult.Key)
 					if getErr != nil {
 						return fmt.Errorf("retrieve target object for verification %q: %w", obj.FilePath, getErr)
 					}
@@ -318,7 +318,7 @@ func migrateObjects(
 					Where("storage_driver = ? AND file_path = ?", sourceDriver, obj.FilePath).
 					Updates(map[string]any{
 						"storage_driver": targetDriver,
-						"file_path":      targetPath,
+						"file_path":      targetResult.Key,
 					}).Error; err != nil {
 					return fmt.Errorf("update migrated object %q: %w", obj.FilePath, err)
 				}

internal/apps/upload/storage_ops.go

@@ -67,21 +67,4 @@ func currentMigrationTargetConfig(ctx context.Context) (storage.Config, bool, er
 	return target, true, nil
 }
 
-func cfgBucket(ctx context.Context, driver storage.Driver) string {
-	cfg, err := storage.LoadConfig(ctx)
-	if err != nil {
-		return ""
-	}
-	switch driver {
-	case storage.DriverS3:
-		return cfg.S3.Bucket
-	case storage.DriverR2:
-		return cfg.R2.Bucket
-	case storage.DriverMinIO:
-		return cfg.MinIO.Bucket
-	case storage.DriverOSS:
-		return cfg.OSS.Bucket
-	default:
-		return ""
-	}
-}
+