fix(simplestorage): use lower helper for safe pointer dereferencing (#21)

Replace unsafe raw pointer dereferencing with the lower helper function
to prevent potential panics when AWS SDK response fields are nil.

Affected functions:
- Put: Etag and VersionId fields
- List: NextContinuationToken field
- ListBuckets: bucket Name and ContinuationToken fields

This makes the code consistent with other methods like Get and Head
which already use the lower helper for optional pointer fields.

Assisted-by: GLM 4.7 via Claude Code
Release-status: cut
Signed-off-by: Xe Iaso <xe@tigrisdata.com>

Author: Xe

simplestorage/buckets.go

@@ -162,14 +162,12 @@ func (c *Client) ListBuckets(ctx context.Context, opts ...BucketOption) (*Bucket
 
 	for _, b := range resp.Buckets {
 		result.Buckets = append(result.Buckets, BucketInfo{
-			Name:    *b.Name,
+			Name:    lower(b.Name, ""),
 			Created: lower(b.CreationDate, time.Time{}),
 		})
 	}
 
-	if resp.ContinuationToken != nil {
-		result.NextToken = *resp.ContinuationToken
-	}
+	result.NextToken = lower(resp.ContinuationToken, "")
 
 	return result, nil
 }

simplestorage/client.go

@@ -267,8 +267,8 @@ func (c *Client) Put(ctx context.Context, obj *Object, opts ...ClientOption) (*O
 	}
 
 	obj.Bucket = o.BucketName
-	obj.Etag = *resp.ETag
-	obj.Version = *resp.VersionId
+	obj.Etag = lower(resp.ETag, "")
+	obj.Version = lower(resp.VersionId, "")
 
 	return obj, nil
 }
@@ -329,9 +329,7 @@ func (c *Client) List(ctx context.Context, opts ...ClientOption) (*ListResult, e
 		HasMore: lower(resp.IsTruncated, false),
 	}
 
-	if resp.NextContinuationToken != nil {
-		result.NextToken = *resp.NextContinuationToken
-	}
+	result.NextToken = lower(resp.NextContinuationToken, "")
 
 	for _, obj := range resp.Contents {
 		result.Items = append(result.Items, Object{