Added plugin manifest to allow for automatic registration of the backend coming in `NSchema 4.0.0.
The S3 lock now records an optional expiry (StateLockInfo.ExpiresUtc) when the lock request carries a time-to-live.
Changed
Updated to the NSchema.Core 4.0.0 lock contract. The S3 state-lock handle releases via the explicit
IStateLockHandle.Release(...) (the handle is no longer IAsyncDisposable), and IStateLock.ForceUnlock is renamed
to IStateLock.Release (returning ValueTask).