feat(project): Establish initial IRTT workspace and protocol definitions

Set up the multi-crate project structure and add the core IRTT protocol with pinned dependencies for reproducible builds.

crates/irtt-proto/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "irtt-proto"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+rust-version.workspace = true
+
+[dependencies]
+hmac = "0.12"
+md-5 = "0.10"
+subtle = "2"
+thiserror = "1"