Add standalone ATO controller in lean Rust.

Pure ato-core logic, minimal HTTP client, JSON config and spec files.
Docker build with tests; integrates with TrainSim over simple REST API.

Co-authored-by: Cursor <cursoragent@cursor.com>

crates/ato-app/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "ato-app"
+description = "ATO controller process — talks to TrainSim over HTTP"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[[bin]]
+name = "ato"
+path = "src/main.rs"
+
+[dependencies]
+ato-core = { path = "../ato-core" }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+
+[lints.rust]
+unsafe_code = "forbid"
+
+[lints.clippy]
+all = "warn"
+pedantic = "warn"