[Tooltip] Missing keyboard trigger (focus)

## Component
Tooltip

## Problem
Tooltips only show on hover, not on focus.

## Suggested Fix
```tsx
const handleFocus = () => setIsOpen(true);
const handleBlur = () => setIsOpen(false);

// Apply to trigger
onFocus={handleFocus}
onBlur={handleBlur}
```

## Impact
Accessibility - Keyboard users cannot see tooltips