[plan] Add additional useful metadata to the guardian plan binary file upload to GCS

### TL;DR

Add additional metadata to the guardian plan file for use in debugging.

Ideas:
- PR number
- GitHub details
- Useful flag information

### Detailed design

_No response_

### Alternatives considered

_No response_

### Additional information

_No response_

Find the guardian plan binary file upload logic, likely in a GCS client or uploader module. Determine what metadata fields (PR number, GitHub details, flags) are available in the context. Look for existing metadata attachment patterns. Verify by checking the upload destination and any related debugging utilities.

由索引模型根据 Issue 内容生成。