Add Support for Batch File Uploads

[mahid797]

Update the existing file upload API to support batch uploads. The API should allow multiple files to be uploaded in a single request, with appropriate validation and error handling for individual files in the batch. Additionally, integrate the updated Upload Modal frontend with the backend to ensure seamless functionality.

---

Tasks

• Modify the existing file upload API (/api/documents/upload) to handle multiple files in one request.
• Update validation logic to:
  • Ensure each file meets the allowed formats and size limits.
  • Return specific error messages for invalid files while continuing to process valid ones.
• Save metadata for each uploaded file to the database.
• Add logic to rollback or clean up partial uploads if the batch processing fails.
• Ensure proper error handling and logging for batch uploads.
• New Task: Integrate the updated Upload Modal with the backend:
  • Ensure the modal triggers the batch upload API correctly.
  • Update the modal to display server-side errors (e.g., invalid files, upload failures) as toasts or in the UI.
  • Show a success message upon completion of the upload process.
  • Validate that all uploaded files appear in the document list on successful submission.

---

Notes

• This API must be backward compatible with single-file uploads.
• Review the related issue (Update File Upload Modal #132) to better understand requirements and align the backend functionality accordingly.
• [Update]: The Upload Modal Issue Update File Upload Modal #132 has been reviewed and merged into the master branch via PR feat/new upload modal #129. Ensure that the updated Upload Modal aligns with the API and functionality.
• [Update]: If certain functionalities\UI are too complex or time-consuming to implement, they should be skipped due to the approaching deadline.