chore: add backoff and retry logic to paperstack wflow

[GangGreenTemperTatum]

aims to close #1

• Increased GitHub workflow timeout to 2 hours
• Added batch processing of papers (5 per batch) with 10-second pauses between batches
• Implemented exponential backoff with jitter for API failures
• Extended retry logic (5 attempts) with more aggressive timeouts
• Set Notion client timeout to 60 seconds
• also updated the workflow versions to hashed versions and updated gitignore for MacOS files

successful ✅ https://github.com/dreadnode/paperstack/actions/runs/14971585333/job/42053558636?pr=2