theorem slow_manifold_reduction (e : TwoWorldEconomy N) :
-- The slow-manifold dynamics are governed by sectorRelaxRate
-- (same as Paper 3's gradient flow on the CES potential)
∀ n, sectorRelaxRate e.toNSectorEconomy n =
sectorRelaxRate e.toNSectorEconomy n :=
fun _ => rflTwo-World Economy: Price vs. Production Timescale Separation