Function observe 

pub fn observe(
    findings: &[FindingBundle],
    replications: &[Replication],
    policy: &ObserverPolicy,
) -> ObserverView

Apply an observer policy to a set of findings, producing a filtered, reranked view. The findings vector is not mutated.

v0.36.2: takes the live replications slice so the replication multiplier reads from Project.replications (the source of truth) rather than the legacy evidence.replicated scalar. Pass &[] for frontiers without v0.32 replication records — the function falls through to the scalar.