Add documentation, refactor public-facing API

ldctl/Cargo.toml

@@ -1,6 +0,0 @@
-[package]
-name = "ldctl"
-version = "0.1.0"
-edition = "2024"
-
-[dependencies]

ldctl/src/main.rs

@@ -1,3 +0,0 @@
-fn main() {
-    println!("Hello, world!");
-}