`campaignJsonMutationRoute` now builds every JSON POST route under /campanha —
`isSameOriginRequest` had been copied into five of them, so the CSRF policy was
failing open by omission; a convention guard sweeps all of `src/app` and names
its three exceptions. `postCampaignJson` is the only place that spells
`credentials: 'same-origin'`, and `useCampaignCellAutosave` is the debounce /
abort / revert / flush-on-close machine the quick-edit cells shipped three
times.
The shell keeps the `aria-live` region outside the Popover/Drawer, since closing
is what commits and it was unmounting the node that would announce the result;
`variant="sheet"` took a `footer` slot, which let the signal control drop the
overlay it only kept for one button.
Two bugs the extraction made visible: a revert issued while a different payload
was in flight was dropped silently, and `change()` never cleared a past failure,
which outranks everything the live region would otherwise say.
