More info in Milleage data

[MARMdeveloper]

Summary

Closes #187

Adds energy cost, total energy consumption and average efficiency (Wh/km) to all levels of the Mileage screen (lifetime, year, month, day). Also improves layout, unit consistency and formatting throughout the screen.

Changes

Data layer

• Load all charges in parallel with drives in loadAllDrives() using async/await
• Calculate energy cost per year/month/day in-memory from allCharges, same pattern as distance and energy — no Room queries needed
• Add totalEnergyCost: Double? to YearlyMileage, MonthlyMileage and DailyMileage

ViewModel

• Add totalLifetimeEnergy, avgLifetimeEnergyDistance and totalLifetimeEnergyCost to MileageUiState
• Add yearTotalEnergy, avgYearEnergyDistance and yearTotalEnergyCost to MileageUiState
• Add currencySymbol and units to MileageUiState, loaded from SettingsDataStore and car status

UI

• SummaryRow: add second row showing average efficiency, total cost and total energy
• YearRow / MonthRow: add second line with cost and efficiency, reorganized into two aligned columns — distance and cost on the left, drive count and efficiency on the right
• MonthSummaryCard / DaySummaryCard: add third stat row with total energy and cost; replace average energy (kWh/drive) with average efficiency (Wh/km)
• Use UnitFormatter.formatEfficiency() for efficiency values (respects imperial units)
• Use currencySymbol from settings instead of hardcoded €