For agents, on top of README.md, which they read first.

Notes for agents

This crate is the only one in Aldebaran that names worker. Keep it small: anything that is only http belongs in aldebaran-axum, anything pure in the crate it is about.

failure must carry no request. It is for the Worker's own faults (a bad variable, a missing asset), the same rule as aldebaran-log.