The development stacks now run Garage instead of MinIO which is
deprecated.
Garage is a bit stricter than MinIO:
- key IDs and secrets must be at least 8 and 16 characters long
- requests must be signed for its region, so every development env now sets
AWS_S3_REGION_NAME=local;
- cross-origin requests are denied unless the bucket CORS rules allow
them, so a one-shot aws-cli container allows the frontend origin to
upload files straight to the bucket.