Build a toast notification system

• Expose an imperative API usable from anywhere: toast.success(msg), toast.error(msg), toast.info(msg) returning an id, plus toast.dismiss(id)
• A ToastContainer renders the active toasts; the API must work without passing props through the tree (a small store plus useSyncExternalStore or context)
• Each toast auto-dismisses after a configurable duration (default 4 seconds); hovering a toast pauses its timer and leaving resumes with the remaining time
• A position option (top-right, bottom-center and so on); a max limit of visible toasts, with extra ones queued and shown as space frees up
• Each toast has a close button, and error toasts stay longer or until dismissed
• Screen readers are told: a container with aria-live="polite" (and role="alert" for errors)
• Toasts stack without layout jumps; removing one animates the others into place

Only after every requirement works.

• Pause all timers while the tab is hidden
• Action button on a toast (for example Undo) and a promise helper toast.promise()
• Deduplicate identical messages shown within a short window