The backend no longer mentions MinIO anywhere: MinioClient -> GarageClient
(minio_client.py -> garage_client.py), MINIO_* env vars -> GARAGE_*, and
the `minio` Python package is replaced with `boto3` (AWS's generic S3
client) since Garage is the only storage backend this project targets
now. S3 API semantics are unchanged, so document_service.py's behavior
is identical — this is a naming and dependency swap, not a logic change.
Also updates test fixtures/names (FakeMinioClient -> FakeGarageClient,
FakeMinioSDK -> FakeS3SDK) and storage/README.md, which no longer frames
Garage as a MinIO replacement (that migration note has served its purpose
now that no MinIO reference remains in the codebase).
Backend: 54/54 tests passing. Frontend: 38/38 tests passing (unaffected,
verified for regressions since it talks to the backend only through the
unchanged REST API).
MinIO's community edition has been trimming features and its licensing
direction has grown less predictable. Garage (AGPL, purpose-built for
self-hosting) is a drop-in S3-compatible replacement — no changes needed
to backend/app/minio_client.py, which talks to the S3 API generically.
Deployed independently from the app stack (storage/docker-compose.yml),
same separation MinIO had. Single-node config (replication_factor = 1)
matching this project's learning/small-team scope. init-garage.sh handles
the one-time layout assignment + bucket creation Garage requires that
MinIO didn't (MinIO auto-creates buckets via API; Garage needs an
explicit `garage bucket create` step).
