Core re-checks dest when building the summary Bloom filter, rebuilding
a peer's broadcast send queue, and emitting a broadcast, so a store
whose for_each_broadcast_id yields addressed ids can't leak them into a
summary or forward them (expired) as broadcasts (review S11).
Adds UnfilteredStore, a test store whose iterators yield every held id,
released and broadcast ones included, pinning spec §4's 'core never
trusts a backend's filtering' for custody, acks and summaries (B8).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>