Refactor storage service only

[Glorie27]

Refactor Storage Service Implementation

This PR refactors the storage service module to improve clarity, structure, and maintainability.

Changes made:

• Improved store_uploaded_object function for better file handling
• Cleaned up storage processing workflow
• Standardized error handling and response structure
• Improved integration between repository and service layers
• Ensured correct file path resolution and storage consistency

Testing:

• Verified upload endpoint via FastAPI /docs
• Confirmed file storage and retrieval works correctly
• Checked background processing flow for queued storage objects

Notes:
This refactor focuses only on the storage service module and does not affect other system components.

[Glorie27]

Hi, I have completed the storage service refactor as requested.

Please let me know if any changes are needed. I’m happy to adjust anything required for the review.

Thank you.