feat(algebra/algebra/spectrum): show the star and spectrum operations commute (#12351)
feat(algebra/algebra/spectrum): show the star and spectrum operations commute (#12351)

This establishes the identity `(σ a)⋆ = σ a⋆` for any `a : A` where `A` is a star ring and a star module over a star add monoid `R`.





leanprover-community/mathlib,leanprover-community/mathlib