A tooltip — a small top-layer label shown on hover/focus of its trigger.
<.tooltip id="copy-tip" text="Copy to clipboard">
<.button icon_only aria-label="Copy">
<svg class="sk-glyph" viewBox="0 0 24 24">…</svg>
</.button>
</.tooltip>The inner block is the trigger; the SkuaTooltip hook shows the label on
pointer-enter / focus and hides it on leave / blur / Escape. The label lives
in the browser top layer (Popover API) so no ancestor overflow can clip it,
and the hook wires aria-describedby from the trigger to the label.