**Toast** — transient notification or inline alert with a tone-colored left edge. Use for save confirmations, scan results, and playout-build failures.

```jsx
<Toast tone="ok" title="Channel saved" message="Retro Cartoons is now on air." onClose={dismiss} />
<Toast tone="error" title="Playout build failed" message="No items match the schedule." />
```

Props: `tone` (info·ok·warn·error), `title`, `message`, `onClose`.
