Meter/consumer entity-page routing evidence memo

Artem-requested read-only production/schema/dashboard audit. Establish Device↔GridElement linkage, whether gs_guid grid pipeline can hydrate MeterState, Explorer routing, and consumer telemetry/config posture. Save full evidence memo at specs/active/20260802-composable-entity-detail-pages/implementation/m1-meter/meter-consumer-routing-findings.md. No code changes or push.