* fix(audit): resolve AB-BA lock-order deadlock between registry and stream_cancellers (backlog#961)
`AuditSystem::runtime_status_snapshot` acquired `stream_cancellers.read()`
before `registry.lock()`, while every other path that holds both locks
(`clear_runtime_targets`, `AuditRuntimeFacade::replace_targets`) acquires
`registry` first. Under concurrency (e.g. admin status polling racing a
config reload) this AB-BA ordering could deadlock the whole audit control
plane with no self-recovery.
Reorder `runtime_status_snapshot` to acquire `registry` before
`stream_cancellers`, unifying the global lock order to
`registry -> stream_cancellers` across all double-lock paths, and add a
multi-threaded regression test that hammers both critical sections with a
timeout guard to fail fast if the ordering regresses.
Refs: https://github.com/rustfs/backlog/issues/961
* docs(audit): reword AB-BA to ABBA to satisfy typos check (backlog#961)
