Add generic ENLYZE power meter pipeline

db/power_meter_grafana.sql

@@ -0,0 +1,14 @@
+-- Set :meter, :from and :to from Grafana variables.
+-- Current power:
+SELECT timestamp AS "time", active_power_total_kw AS "value"
+FROM power_meter_readings WHERE meter = '${meter}' AND $__timeFilter(timestamp);
+
+-- Energy today / rolling 24h (counter increments are reset-safe).
+SELECT COALESCE(sum(energy_delta_kwh), 0) AS kwh
+FROM power_meter_readings
+WHERE meter = '${meter}' AND timestamp >= now() - interval '24 hours';
+
+-- Frequency and outages in selected period.
+SELECT min(grid_frequency_hz) AS frequency_min_hz, max(grid_frequency_hz) AS frequency_max_hz,
+       COALESCE(sum(outage_delta), 0) AS outages
+FROM power_meter_readings WHERE meter = '${meter}' AND $__timeFilter(timestamp);