Write run_agent: who is on call for a service this week

Paging the right person takes two lookups: who owns the service, then who covers that team this week.

Your task

Write run_agent. It names the person on call for a service in a given week.

• search(query) returns the ids of documents containing that text, shortest first
• fetch(doc_id) returns that document, or None when the id does not exist
• a service card says which team owns the service; the team's rota says who covers each week
• answer with the person's full name, or not found when the card, the rota or that week is missing
• each scenario carries a token budget; going over it fails that scenario

At submit the suite runs your agent against services and rotas you have not seen.