Improve AI Agent JavaScript

Improved some of the JavaScript in the MR here:
https://git.drupalcode.org/project/ai_agents/-/merge_requests/79

Nothing changes for the user, it just removes jQuery, adds Drupal Behaviors, along with once().

Looks good and useful to remove jQuery: RTBC.

Added a couple of comments, changing the status to NW. Feel free to change in case you feel these changes are not so important.