feat: optional S3-compatible storage for uploaded images, instead of the local upload directory

docs/deployment.md

@@ -8,7 +8,7 @@ RenewCMS ships as **one self-contained executable**. It serves:
 | `/healthz` | Liveness check, returns `200 ok`        |
 | `/*`       | The Vue SPA (embedded), with fallback to `index.html` for client-side routes |
 
-Runtime state includes the SQLite database (`DB_FILE`, or a MySQL/MariaDB server, see [Using MySQL or MariaDB](#using-mysql-or-mariadb)), uploads (`UPLOAD_DIR`), and update records, staged binaries and backups beside the database. Running a release binary needs no Go, Bun or Node installation. Browser updates additionally require Linux with systemd and the helper setup below.
+Runtime state includes the SQLite database (`DB_FILE`, or a MySQL/MariaDB server, see [Using MySQL or MariaDB](#using-mysql-or-mariadb)), uploads (`UPLOAD_DIR`, or an S3-compatible bucket with `STORAGE_DRIVER=s3`, see [configuration.md](configuration.md#image-storage)), and update records, staged binaries and backups beside the database. Running a release binary needs no Go, Bun or Node installation. Browser updates additionally require Linux with systemd and the helper setup below.
 
 To run it in a container instead, see [docker.md](docker.md). The published image `git.floriansylvain.fr/fsylvain/renewcms` is upgraded with `docker compose pull && docker compose up -d`. Tags are `vX.Y.Z`, `X.Y.Z`, `X.Y` and `latest` for a stable release, and `vX.Y.Z-<pre>`, `X.Y.Z-<pre>` and the moving `<pre-name>` (`beta`, `rc`) for a pre-release, which never moves `latest`. Maintainers publish with `task docker:publish` after `docker login git.floriansylvain.fr`; there is no CI. See [Maintainer: publishing](docker.md#maintainer-publishing).