Build a tooltip

• <Tooltip content="..." placement="top"> wraps a trigger and shows the tooltip on hover and on keyboard focus, and hides it on mouse leave, blur and Escape
• Supports top, bottom, left and right placement with a small gap and an arrow or offset
• Flips to the opposite side when there is not enough room in the viewport, and shifts along the edge to stay fully visible
• A show delay (for example 300 ms) and a short hide delay avoid flicker; timers are cleared on unmount
• The trigger gets aria-describedby pointing at the tooltip, which has role="tooltip"
• The tooltip is rendered in a portal and positioned from the trigger's getBoundingClientRect() so overflow clipping and z-index of ancestors do not cut it off

Only after every requirement works.

• Reposition on scroll and resize while visible
• Tooltip stays open while the pointer moves onto it (hoverable content)
• Pointer-events and touch handling for long press