Function render_route_label_at 

pub fn render_route_label_at(
    painter: &mut Style<'_, impl Renderer>,
    route: &Route,
    at: LocAndDirection,
    color: Role,
)

Draw one of route’s labels at at, oriented along the wire there. An unnamed route shows the faint “add name” prompt (mirroring the pin placeholder); a named one shows the name in color.