Snapshots index/view/associations returned each snapshot's events without
a monitor check, and Snapshots and Tags add/edit attached any event ids,
so a user could add a denied monitor's event to a snapshot and then read
it back. Attaching now needs view on each event, listed events are
filtered to viewable monitors, and ids are pinned. Tags' existing
filters also match nothing, rather than everything, for a user denied
every monitor.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>