fix: load local env file correctly in backup script

scripts/backup.sh

@@ -28,9 +28,14 @@ has_command() {
 load_env() {
   [ -f "$ENV_FILE" ] || fail "Env file not found: $ENV_FILE"
 
+  case "$ENV_FILE" in
+    */*) env_path="$ENV_FILE" ;;
+    *) env_path="./$ENV_FILE" ;;
+  esac
+
   set -a
   # shellcheck disable=SC1090
-  . "$ENV_FILE"
+  . "$env_path"
   set +a
 
   : "${DB_HOST:?DB_HOST is required in $ENV_FILE}"