refactor(restore)!: rsync volumes directly on the host, drop alpine-rsync

Restore now resolves the target volume's mountpoint via docker volume
inspect and rsyncs into it directly, mirroring how the backup path
already reads the mountpoint; the alpine-rsync container and the
--rsync-image flag are gone. The e2e harness mounts /var/lib/docker
read-write in the test container so the direct restore can write, the
same way baudolo runs as root on a real host.

BREAKING CHANGE: the restore 'files' subcommand no longer accepts
--rsync-image; the caller must have write access to the docker volume
root (root on the host), which is baudolo's normal privilege.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/baudolo/restore/__main__.py

@@ -38,10 +38,6 @@ def main(argv: list[str] | None = None) -> int:
     # ------------------------------------------------------------------
     p_files = sub.add_parser("files", help="Restore files into a docker volume")
     _add_common_backup_args(p_files)
-    p_files.add_argument(
-        "--rsync-image",
-        default="ghcr.io/kevinveenbirkenbach/alpine-rsync",
-    )
     p_files.add_argument(
         "--source-volume",
         default=None,
@@ -95,7 +91,6 @@ def main(argv: list[str] | None = None) -> int:
             return restore_volume_files(
                 args.volume_name,
                 bp_files.files_dir(),
-                rsync_image=args.rsync_image,
             )
 
         if args.cmd == "postgres":