//! # toddy
//!
//! Native GUI renderer binary. Three execution modes:
//!
//! - **Windowed (default):** `toddy` -- Full iced rendering with real
//! windows and GPU. Production mode. Reports `"mode": "windowed"`.
//! - **Headless:** `toddy --headless` -- No display server. Real
//! rendering via tiny-skia with persistent widget state. Accurate
//! screenshots after interactions. For CI with visual verification.
//! - **Mock:** `toddy --mock` -- No rendering. Core + wire protocol
//! only. Stub screenshots. For fast protocol-level testing from
//! any language.
//!
//! All modes handle scripting messages (Query, Interact, TreeHash,
//! Screenshot, Reset) for programmatic inspection and interaction.
//!
//! Wire codec auto-detection: the first byte of stdin determines the format
//! (`{` = JSON, anything else = MessagePack). Override with `--json` or
//! `--msgpack`.
/// Entry point for the toddy renderer.
///
/// Extension packages create a `ToddyAppBuilder`, register their extensions,
/// and pass it here. The default `main.rs` simply passes an empty builder.