refactor(frontend): hover tooltips on react-aria-components - #4000

Design-system prep, step 2: hover tooltips on react-aria-components

Stacked on #3999. WithTooltip (tippy) becomes ui-components/Tooltip, in react-aria's composition shape so call sites won't change again as more components move to react-aria:

<TooltipTrigger>
  <IconButton … />
  <Tooltip>{t("common.delete")}</Tooltip>
</TooltipTrigger>

• react-aria-components and react-aria added, pinned to the same release: a second copy of react-aria would carry its own React contexts and silently break the trigger wiring
• buttons are triggers on their own; TooltipTarget marks static content and keeps it out of the tab order
• timing per Spectrum's guideline via tooltipDelay: immediate for help icons, short (300 ms) by default, long (1500 ms) for hints on larger surfaces; after the warm-up, neighboring tooltips open instantly; a tooltip closes 300 ms after the pointer leaves (a hover-revealed trigger stays invisible rather than hidden, so the closing tooltip keeps its anchor)
• look unchanged; storybook loads index.css now; Tooltip stories
• tippy stays for the three click popovers until the menus step