List serving capacity lanes and their members (platform admin)

The lane view, derived by the same pipeline that drives rollouts, so a surface can never narrate a different split than the controller executes: per lane, its members oldest first with their live catalog weight and share, the green if the lane is rolling, and a flag when the two sides run different pool policies. Filter by publicModelId and nodePool to answer "does this lane already have a green" before creating one.