registries: no need for static mut or unsafe + use std's LazyLock

[cormacrelf]

This fixes nightly rustc yelling about:

error: creating a shared reference to mutable static is discouraged
  --> src/user_input/trait_serde.rs:69:37
   |
69 |         let mut registry = unsafe { AXISLIKE_REGISTRY.write().unwrap() };
   |                                     ^^^^^^^^^^^^^^^^^^^^^^^^^ shared reference to mutable static
   |
   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2024/static-mut-references.html>
   = note: shared references to mutable statics are dangerous; it's undefined behavior if the static is mutated or if a mutable reference is created for it while the shared reference lives

And drops a dependency.

Ref #662 which had build failures.

[alice-i-cecile]

Very pleased to have that gone. Thank you!