//! TUI module — groups all Ratatui front-end components.
//!
//! | Submodule | Responsibility |
//! |------------------|---------------------------------------------------------|
//! | `app` | Application state machine & channel polling |
//! | `events` | Keyboard event → state-transition mapping |
//! | `flash_runner` | Tokio task that drives the privileged flash child |
//! | `ui` | All ratatui `Frame` rendering (one function per screen) |