Add visual indicators to distinguish hourly aggregated data from
original 15-minute interval data in ApexCharts output.
Changes:
- Chart title: Append localized suffix like "(Ø hourly)" / "(Ø stündlich)"
- Y-axis label: Append "(Ø)" suffix, e.g., "øre/kWh (Ø)"
The suffix pattern avoids confusion with Scandinavian currency symbols
(øre/öre) which look similar to the average symbol (Ø) when used as prefix.
Added hourly_suffix translations for all 5 languages (en, de, sv, nb, nl).
Impact: Users can now clearly see when a chart displays averaged hourly
data rather than original 15-minute prices.
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