GitLab

* [Enhancement][Pipeline] Improve pipeline stage information handling and copy stage detection

- Added detailed documentation for the PipelineStageInfo structure to clarify its parameters.
- Enhanced the VisitStmt_ method to handle annotations for pipeline order and stage more effectively.
- Implemented logic to determine if a stage is used by a copy operation, adjusting the stage assignment accordingly.
- Processed the tail copy stage to ensure correct ordering and stage assignment in the pipeline planning process.

* lint fix