When there is a need for Wiki admins or people with a specific role to modify the system prompt, they should be able to edit the system prompt just by modifying the content of a wiki page.

Ideally, a config variable should be used to enable this:

$wgWandaCustomPrompt = 'Title_of_the_page';

When this variable is set, the LLM should use the system prompt from the wiki page. If not set, Wanda's instructions in the code should automatically be used.