feat(set_theory/surreal/basic): relabellings preserve being numeric (#14406)
feat(set_theory/surreal/basic): relabellings preserve being numeric (#14406)



Co-authored-by: Yaël Dillies <aef64c2b10aaee4bd1b6422c57104205a3c50e06@gmail.com>

leanprover-community/mathlib,leanprover-community/mathlib