Set up cargo workspace and shared crate

tta/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "tta"
+version = { workspace = true }
+edition = { workspace = true }
+
+[dependencies]
+
+[lints]
+workspace = true

tta/src/lib.rs

@@ -0,0 +1,3 @@
+pub fn greet(name: &str) -> String {
+    format!("Hello {name}!")
+}