pub async fn preload_community(invite: &CommunityInvite)Expand description
Warm a community’s primary-channel first page into the RAM preload cache BEFORE the user joins,
so accepting opens a populated chat instead of paying the join sync. RAM-only and side-effect-
free: builds the member view from the bundle WITHOUT persisting (nothing is stored for a
community the user may decline), fetches one page, and stashes it keyed by community id (the
fetch also warms the relay connection). Best-effort — any failure just leaves Join to sync
normally. Spawn this behind a SessionGuard; promotion on Join re-validates freshness.