v2.1.0: feat: Enhance tooltip functionality with rich content support

- Updated the tooltip system to utilize a single body-level #vui-tooltip that is fixed in position, preventing clipping by ancestor elements.
- Introduced two types of tooltips: a plain text bubble for [data-tip="text"] and a rich bubble for .vui-tip elements containing a <template>.
- Implemented logic to toggle visibility based on mouse events, focus, and touch interactions, improving accessibility on mobile devices.
- Added styling for rich tooltips, including tone-based color adjustments and layout for nested widgets.
- Updated documentation to reflect new tooltip capabilities and usage examples.