Function normalize_mount 

pub fn normalize_mount(raw: &str) -> String

Normalize a component mount to a storage/URL key prefix: strip the surrounding slashes. "/app", "app/", "/app/" → "app"; "/", "" → "" (the service root).

One producer on purpose — the publisher’s key prefix, the route-path cross-check and the front door’s key lookup must all agree on what /app means down to the byte, and three copies of trim_matches('/') is how they stop agreeing.