First line: a chrome-free square icon control for toolbars and row affordances.

```jsx
<IconButton icon="Share" label="Поделиться" />
<IconButton icon="Star" label="В избранное" />
<IconButton icon="Panel" label="Боковая панель" size="md" />
```

Notes
- Muted glyph that fills with `--secondary` on hover — never carries primary colour at rest.
- Always pass `label` for the tooltip + a11y. Reach for `Button` when the action needs visible text.