v0.1.0

The first release. Show these once, stacked, then remember they were seen:
for release notes after an app update, a welcome message, new posts, or anything
else that needs that UX.

Added

• <WhatsNew load={(since) => WhatsNewGroup[]}>: on the first load after a
  refresh or login, the groups of cards newer than what this person last saw.
  since is the newest cursor they were shown (null on a first visit); groups
  come back newest first, as { id, label?, date?, cards }, and a group with no
  cards is skipped. Cursors (a version, a post id, a timestamp) are compared for
  equality only and stored as strings.
• Cards in fancy-app-update's shape (title, description?, image?,
  imageDark?, imageAlt?, id?), plus one optional link,
  action: { label, href }, which closes the notice when followed.
• missed="all" | "latest": stack every newer group (each card labelled with
  its group's label and date when present), or only the newest.
• firstVisit="latest" | "none" | "all": what a first visit shows. "none"
  still records a baseline.
• storage={{ load, save }}, sync or async, defaulting to localStorage
  under storageKey (SSR-safe, touched only in effects). A store that fails to
  load shows nothing.
• Seen on show: the newest cursor shown is recorded once the notice is on
  screen in a visible tab. The README says why, and why "shown" rather than
  "returned".
• open / onOpenChange: a button shows the current cards on demand (the
  page-load notice if it is up, otherwise the newest group).
• labels, position, style, className, cardClassName, depth,
  offset, color, scrollHint, renderCard (told the card's group),
  render, onSeen, onClose.
• Stable data-fancy-whats-new-* handles on the notice (with its mode), every
  card (with its group's cursor) and every control.
• localStorageStore(key), selectNew, withCards, cursorOf exported for
  custom surfaces.
• The cards are fancy-app-update's FeatureCards (>=0.7.0 <2.0), imported
  rather than copied.