a584df052d
Add oss.go with full FileService implementation (SaveFile, SaveBytes, GetFile, DeleteFile, GetFileURL, CheckConnectivity) using aws-sdk-go-v2 with path-style addressing for Aliyun OSS. Includes temp bucket support and unit tests for parseOssFilePath and client creation. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>