Configures an Amazon S3-compatible object store as the file attachment backend. Works with AWS S3, MinIO, Cloudflare R2, Backblaze B2, DigitalOcean Spaces, and other S3-compatible services.

###### Settings

Access Key
  The access key ID (for AWS this starts with `AKIA…`; other providers use their own format).
Secret Key
  The secret access key corresponding to the access key. Stored encrypted at rest.
Region
  The storage region (e.g. `us-east-1`, `eu-west-1`). Leave blank if the provider does not use regions.
Endpoint URL
  For non-AWS providers, enter the full base URL of the S3-compatible API (e.g. `https://s3.eu-central-1.wasabisys.com`). Leave blank for AWS S3.
Bucket
  The name of the bucket to store objects in.

After configuring this provider, select S3 Compatible Storage as the active provider in File Configuration to route uploads here.

###### AWS S3 Setup Notes

1. Create an IAM user with AmazonS3FullAccess (or a scoped policy on the target bucket) and generate an access key.
2. Create the S3 bucket in the desired region with appropriate access controls (Block Public Access recommended).
3. Leave Endpoint URL blank when using AWS S3.