When git push completes, the webhook fires immediately but GCS upload
may still be in progress. This causes KeyError when trying to read
commit objects that haven't been uploaded yet.
Add retry with exponential backoff (1s, 2s, 4s) to handle this race.
🐾 Generated with [Letta Code](https://letta.com)
Co-authored-by: Letta <noreply@letta.com>