Always enforce recovery race-condition invariants with explicit tests

When changing session recovery or projection logic, preserve strict negative invariants around concurrency boundaries and encode each as a clearly named regression test. Verify that stale, superseded, transferred, quarantined, or expired claims are never recovered, promoted, quarantined, awakened, or allowed to advance state. Exercise races at scanner validation, input commit, ownership transfer, cancellation expiry, and selection/redrive CAS boundaries. Include delivery-mode edge cases such as quarantined continuations marked as ordinary steer, and assert both the forbidden side effect and the resulting durable state.