Short or garbled gateway responses are rejected on register count
instead of half-decoding (previously: 'unpack requires a buffer',
OverflowError on garbage scale factors). Scale factors outside
+/-10 and non-finite floats are dropped before they reach line
protocol.
offgrid is written as integer offgrid_state: the existing DB
cannot be migrated (mixed inmem/tsi1 shards block all deletes)
and the old boolean field conflicts with integer writes, which
poisoned the spool - HTTP 400 now drops the batch and logs the
InfluxDB error body instead of re-spooling it forever.
grafana_dashboard.json: fully German dashboard (InfluxQL,
InfluxDB 1.x) with off-grid state, SoC (SoE*SoH/100) and
consumption-source panels; status tiles use integers plus value
mappings because Grafana drops string/boolean fields from
InfluxQL time series.
