Choose an engine for each agent version

Creating a new configuration version now shows an Engine selector. For a Shopping assistant you choose between AISA Light 1.0, AISA Standard 1.0, and AISA Max 1.0: three tiers that trade off response speed against answer quality. New versions default to AISA Standard 1.0. A Custom agent runs on Custom 1.0, its only engine.

The engine is part of the version, so it's fixed once the version is created, like its instructions and its chat tools. To move an agent onto a different engine, create a new version and pick the engine there.