Scalars on the unit of the doubling

The unit of the doubling is the unit in even degree and the zero object in odd degree, so its endomorphisms are those of the unit downstairs: the scalar-unit hypothesis passes to the doubling.

theorem RS.hasScalarUnit_doubled {A : Type u} [CategoryTheory.Category.{v, u} A] [CategoryTheory.MonoidalCategory A] [CategoryTheory.Preadditive A] [CategoryTheory.Linear ℂ A] [CategoryTheory.MonoidalPreadditive A] [CategoryTheory.Limits.HasBinaryBiproducts A] [CategoryTheory.Limits.HasZeroObject A] (hu : HasScalarUnit A) : HasScalarUnit (Doubled A)

The scalar-unit hypothesis passes to the doubling.