Always enforce concurrency and recovery invariants with regression tests

Treat session recovery, promotion, cancellation, and retry boundaries as strict “never” invariants. Reject or quarantine work when ownership has changed, a claim has expired or been superseded, scanner validation fails, continuation input is quarantined, or an exact retry conflicts. Never let these cases recover, promote as ordinary queue/steer work, arm durable wake intent, or mutate context ownership. Add targeted race and replay regression tests that verify durable database rows, event counts, promotion state, recovery errors, and wake counts—not only immediate return values. Confirm invalid work remains inert across projection replay and later recovery scans while unrelated ordinary work can still proceed.