Command-line interface library for Zenith.

Owns all command dispatch, argument parsing (via clap), JSON I/O shaping, and human-readable stdout/stderr formatting.

src/main.rs is kept thin — it only calls [run]. zenith-layout is reached transitively through zenith-scene; the CLI never constructs layout types directly.

Module layout

• cli — clap #[derive(Parser)] types.
• commands/ — one module per subcommand; all business logic is here, operating on in-memory bytes, never touching the FS.
• json_types — serialisable DTOs for JSON output.
• lib.rs — this file: wiring + run() dispatcher + file I/O edge.