fix(alerts): an escalation chain routes an anomaly rule - #2328

🟢 Confidence 10/10 · safe to merge. Routing helpers are pinned on backend, web-data and editor tests; the only unprovable state, member-only chains, is now reported as unknown by design.
_{no findings · tests covered · risk medium}

An escalation chain on a tier now counts as routing an anomaly rule at save, at push, in hub status and in diagnosis, so a chain-only rule saves, pages, and stops being reported unrouted. Server and client agree, and the behavior is tested on both sides.

• anyTierRouted lets a scoped anomaly rule save with only a chain
• tierRoutedUpTo lets a chain-routed anomaly tier send the mobile push
• isRuleRouted clears the unrouted flag and diagnosis copy for chain-only rules
• isAnomalyUnrouted unblocks the editor's save check for chains

Fixed since the last review

• ✅ F2 · Chain-only notification stage never sees a member or schedule page

_{669bf05 · Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}