mathlib

df78eae5 - refactor(geometry/euclidean/angle/unoriented/basic): split out conformal map lemmas (#18210)

refactor(geometry/euclidean/angle/unoriented/basic): split out conformal map lemmas (#18210) Move two lemmas about conformal maps preserving angles to a separate `geometry.euclidean.angle.unoriented.conformal`, so eliminating the dependence of angles on calculus (and use `assert_not_exists` to declare that the basic file should not depend on calculus or conformal maps). None of the other Euclidean geometry results depend on these two lemmas.