Register an AgentBase instance at a URL route
on the server. The agent’s Hono app is mounted at the specified prefix so all of its
endpoints (SWML, SWAIG, debug, post-prompt) become available under that path.
Throws Error if the route is already occupied by another agent.
The agent instance to register.
URL path prefix for this agent (e.g., "/sales"). If omitted, the agent’s own route
property is used. Leading slashes are added and trailing slashes are stripped automatically.
void