Add SHA-256 to proto, wrapping the emsha crate

Implemented-By: Laguna S 2.1 (OpenCode)

Cargo.lock

@@ -16,6 +16,12 @@ dependencies = [
  "proto",
 ]
 
+[[package]]
+name = "emsha"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "998c85fef9015859e22d1a9afa657dc134835a43e95a28fe1413e916ed8b7cb3"
+
 [[package]]
 name = "equivalent"
 version = "1.0.2"
@@ -90,6 +96,7 @@ dependencies = [
 name = "proto"
 version = "0.1.0"
 dependencies = [
+ "emsha",
  "humantime",
  "serde",
  "serde_json",