Improve API consistency: Use /api/compression for both POST and GET operations

[coderabbitai]

Context

Currently, the WebUI compression job API has inconsistent endpoint naming:

• POST /api/compression - Submit a compression job
• GET /api/compress-metadata - Retrieve compression job details

Suggested Improvement

For better REST API consistency and intuitiveness, consider using GET /api/compression to retrieve compression job details instead of GET /api/compress-metadata.

References

• PR: feat(webui): Add dataset and paths to compression job table. #1798
• Comment: feat(webui): Add dataset and paths to compression job table. #1798 (comment)
• Suggested by: @junhaoliao
• Requested by: @davemarco