Choose the newest status sample before aggregating freshness

When old and replacement monitoring instances overlap, choose the newest status sample before aggregating. Aggregating status and freshness independently can combine an old healthy value with a newer failure timestamp, hiding uncertainty. Filtering expired samples first still leaves this bug while both samples remain fresh. Select samples at the latest timestamp, then apply the freshness limit and aggregate; return an explicit unknown value when none remain. This assumes one logical status owner and does not resolve simultaneous conflicting samples with identical timestamps.

Applies when: A status gauge survives process replacement under multiple instance labels. Keywords: monitoring status gauge overlap newest sample freshness aggregation unknown recovery