Chosen over an app-side polling timer specifically to honor NFR-RES-1
("no polling timers running when not recording") — Windows itself
delivers the toast at due_at, and a scheduled toast is cleared by the
OS after it fires, so there's no "already fired" bookkeeping needed in
this app either. Windows-only, matching hardware::dxgi's pattern: the
real WinRT implementation lives in a #[cfg(windows)] submodule behind
plain top-level functions.
Verified against the live Windows toast API (not just compiled): a
throwaway example scheduled a reminder, confirmed
GetScheduledToastNotifications() reported it back with the correct id,
then confirmed cancel() removed it.
iamdoubz
f6e0de5486