feat: split device and power-sensor telemetry charts (#643) (#656)

* feat: split device and power-sensor telemetry charts (#643)

Add telemetry_type TEXT discriminator column across the full stack so
device_metrics rows no longer mix with power_metrics in the same chart.
Python and Ruby ingestors detect the protobuf subtype at write time;
classifySnapshot() provides field-presence fallback for legacy rows.
'Power metrics' chart split into 'Device health' and 'Power sensor'.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: skip typeFilter for aggregated telemetry; add air_quality coverage

- renderTelemetryChart now skips spec.typeFilter when chartOptions.isAggregated
  is true, preventing mixed-bucket aggregated snapshots from losing series data
- renderTelemetryCharts detects the aggregated vs per-packet path and sets
  isAggregated accordingly; typeFilter still applies for per-packet history
- JS tests: extract makeAggregatedNode/makeHistoryNode helpers to eliminate
  fixture duplication; add aggregated-mixed-bucket regression test; move
  type-separation tests onto the history path where filtering actually applies
- Ruby + Python: add air_quality_metrics telemetry_type tests for coverage

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* refactor: reduce test duplication flagged by Sonar

Hoist CHART_NOW_MS/CHART_NOW_SECONDS constants to eliminate 14 repeated
setup lines across renderTelemetryCharts tests.  Extract
expect_stored_telemetry_type helper in app_spec to replace the four
identical with_db/SELECT/expect blocks in telemetry_type inference tests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* web: address review comments

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

data/telemetry.sql

@@ -55,7 +55,8 @@ CREATE TABLE IF NOT EXISTS telemetry (
     soil_moisture           INTEGER,
     soil_temperature        REAL,
     ingestor                TEXT,
-    protocol                TEXT NOT NULL DEFAULT 'meshtastic'
+    protocol                TEXT NOT NULL DEFAULT 'meshtastic',
+    telemetry_type          TEXT
 );
 
 CREATE INDEX IF NOT EXISTS idx_telemetry_rx_time ON telemetry(rx_time);