New register shows instantly STAGING

Not a data/caching issue — the list already reads fresh. It was the fire-and-forget router.refresh() race: the Add-register dialog closed before the re-render landed, so the new row popped in a beat later. Fixed with optimistic UI — the registers admin now mirrors the list in local state and inserts the new register (with its real ID, returned by the create action) the instant it's created; router.refresh() then reconciles. Only inserts for the shop currently in view; edit / delete / bulk flows unchanged.