[Tooltip] Missing ARIA role and describedby

## Component
Tooltip

## Problem
Missing proper ARIA attributes.

## Suggested Fix
```tsx
// Trigger
<button aria-describedby={isOpen ? tooltipId : undefined}>
    {children}
</button>

// Tooltip
<div role="tooltip" id={tooltipId}>
    {content}
</div>
```

## Impact
Screen readers cannot associate tooltip with trigger