* fix(events): serialize DB deletion with thread writers
* fix(runs): delete thread history without dropping reservations
* fix(feedback): support owner-scoped thread cleanup
* fix(threads): clean persisted records on deletion
* fix(threads): correct the feedback cleanup rationale
* test(runs): drop the wall-clock probe from the in-flight delete test
* docs: record the thread-delete and event-store fence contracts
* fix(threads): preserve legacy event-store delete compatibility