A new entry-tier engine, AISA Extra Light 1.0

The Engine selector on a new configuration version for a Shopping assistant has a new option: AISA Extra Light 1.0. It sits below AISA Light 1.0 as the lowest-cost tier: it still answers well, it just responds more slowly. Pick it when you want to favor cost over speed.

It joins the existing engines (AISA Light 1.0, AISA Standard 1.0, AISA Max 1.0). All stay selectable; adding this one doesn't remove any of them.

No default changed: new shopping assistant versions still default to AISA Standard 1.0. As with any engine, once a version is created its engine is fixed; create a new version and pick a different one to switch.