Add monthly offsite restore tests and automatic cleanup

lib/restore-test-remote.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+# Private bridge to the existing crypt/environment validation and rclone flags.
+set -Eeuo pipefail
+LIB_DIR=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=lib/common.sh
+source "$LIB_DIR/common.sh"
+CONFIG_FILE=${1:?Missing config}
+shift
+load_config
+check_remote >&2
+# rclone is restricted to read operations here, including metadata reads.
+case ${1:-} in lsf|cat) rc "$@" ;; *) die 'Unsupported restore-test remote operation' ;; esac