filterLifecycleEntries

Filter a lifecycle StreamChannel to only the entries whose namespace lies within the subtree rooted at path.

Returns an AsyncIterable whose iterator yields every entry whose namespace either equals path or is a descendant of it. Iteration begins at startAt, so callers can capture the log's current size at construction time to skip entries emitted before the caller existed (e.g. a subgraph stream discovered mid-run shouldn't replay the root's started).