When user uploads multiple large PDFs, the API times out - can we do it one by one?

[woodthom2]

Description

When user uploads multiple large PDFs, the API times out - can we do it one by one?

How to Reproduce

1. Upload 15 PDFs simultaneously
2. There is a single API call

Expected Behavior

Sequentially chain the API calls in series

[ronnyTodgers]

Fixed by #62 (merged into master). Root cause: all uploaded files went to /text/parse in a single request with a 15 s client timeout and three blind retries, so a batch of large PDFs timed out and was re-sent while the server was still working on the first attempt. Files are now parsed one per request, in series, with a progress toast, and any file that fails is reported individually instead of failing the batch.

The same change is live on the consolidated app at https://meta.harmonydata.ac.uk/harmony. The legacy /app deploys from the release branch, so it needs a master → release merge to pick this up.