[Spring 2026] Verify File Service readiness for user onboarding

[llam36]

Context

• File service is fully implemented, but we need to confirm if it's ready to be released to users
• Need a demo walkthrough of a React app using the File service SDK to upload/download files correctly

Requirement

React app:

• Create a dummy react app with juno-sdk installed
• The app should have frontend components to upload and download files

Backblaze:

• Create a Backblaze account and api keys: https://www.backblaze.com/cloud-storage

Juno File service SDK:

• Follow the steps to use file service: docs
• Use the Juno dashboard to register all the necessary info
• Create a pre-signed URL to upload a file using the juno-sdk
• In the React app, upload a text file test.txt to Backblaze using the pre-signed URL and show that the file is successfully uploaded in the Backblaze portal (with the correct file name)
• Create a pre-signed URL to download test.txt using the juno-sdk
• In the React app, use the pre-signed URL to download the file and show that it has been downloaded successfully

PR requirement

• Briefly list what you did
• Video showing all steps taken in Juno Dashboard and the upload/download process (React app + Backblaze portal showing the files)