cargo: add ref-cast dependency

It helps to implement transparent conversion from &str to &Wrapped(str). We
could instead wrap the reference as Wrapped<'a>(&'a str), but it has various
drawbacks. Notably we can't implement Borrow and Deref because these traits
require a reference in return position.

Since the unsafe bits are pretty small, we can instead implement cast functions
without using the ref-cast crate. However, I believe we'll trust ref-cast more
than hand-crafted unsafe code.

https://crates.io/crates/ref-cast
https://docs.rs/ref-cast/1.0.20/ref_cast/attr.ref_cast_custom.html

Cargo.lock

@@ -1681,6 +1681,7 @@ dependencies = [
  "rand",
  "rand_chacha",
  "rayon",
+ "ref-cast",
  "regex",
  "rustix",
  "serde",
@@ -2380,6 +2381,26 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "ref-cast"
+version = "1.0.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "acde58d073e9c79da00f2b5b84eed919c8326832648a5b109b3fce1bb1175280"
+dependencies = [
+ "ref-cast-impl",
+]
+
+[[package]]
+name = "ref-cast-impl"
+version = "1.0.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f7473c2cfcf90008193dd0e3e16599455cb601a9fce322b5bb55de799664925"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.37",
+]
+
 [[package]]
 name = "regex"
 version = "1.10.2"

Cargo.toml

@@ -65,6 +65,7 @@ prost-build = "0.11.9"
 rand = "0.8.5"
 rand_chacha = "0.3.1"
 rayon = "1.8.0"
+ref-cast = "1.0.20"
 regex = "1.10.2"
 rpassword = "7.3.1"
 rustix = { version = "0.38.25", features = ["fs"] }

lib/Cargo.toml

@@ -43,6 +43,7 @@ prost = { workspace = true }
 rand = { workspace = true }
 rand_chacha = { workspace = true }
 rayon = { workspace = true }
+ref-cast = { workspace = true }
 regex = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }