Add four optional parameters to the get_chartdata service:
- include_energy: Include raw energy/spot price (default: false)
- include_tax: Include tax component (default: false)
- energy_field: Custom field name (default: energy_price)
- tax_field: Custom field name (default: tax)
Custom field names allow direct compatibility with ApexCharts
and other charting tools without post-processing.
All code paths (all/segments/none insert_nulls modes) and the
last-interval handler include energy/tax when enabled.
Added translations for all 5 languages (en, de, nl, nb, sv).
Impact: Users can include price composition data in chart exports,
enabling visual breakdowns of energy cost vs. taxes in dashboards.