Validate alert identity at the query, annotation and notification-group boundaries

Provider-aware alert messaging requires identity to survive three boundaries: query aggregation, rule annotation interpolation, and notification grouping. A template reading CommonLabels cannot reliably display a provider if different providers share one notification group. Verify bounded provider/operation labels in live evaluated instances, group the dedicated route by those labels before a general route, and preview both firing and resolved titles plus alerts without those labels. Preserve unrelated route ordering and timing. Non-delivery template previews prove rendering only; they do not prove actual notification delivery or controlled alert firing/recovery.