Replace the shared force and republish booleans with request tickets.
A completed publication now acknowledges only requests captured when it
began, so a concurrent immediate or cadence-break request survives.
Prepare each acquired content frame into one of two private GPU
candidates so the IddCx frame can be released without copying it to
IVSHMEM immediately.
Wake a high-resolution publisher at the client deadline and send the
newest completed candidate. Preserve accumulated damage across
superseded candidates, include the scheduling hold in end-to-end timing,
and keep transport work on the existing physical copy queue.
