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>

Dockerfile

@@ -0,0 +1,17 @@
+FROM rust:1.85-bookworm AS builder
+WORKDIR /src
+COPY Cargo.toml ./
+COPY crates ./crates
+COPY config ./config
+COPY spec ./spec
+RUN cargo test --workspace && cargo build --release -p ato-app
+
+FROM debian:bookworm-slim
+RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+COPY --from=builder /src/target/release/ato /usr/local/bin/ato
+COPY config/ato.default.json /etc/ato/ato.default.json
+ENV ATO_CONFIG=/etc/ato/ato.default.json
+USER nobody
+WORKDIR /etc/ato
+ENTRYPOINT ["/usr/local/bin/ato"]