- Add BatteryHistory component with 24h voltage/SoC% dual-axis chart - Canvas-based visualization (voltage left axis, SoC% right axis) - Green bands mark charge cycles - Auto-refresh every 30 seconds - Integrated into Battery tab alongside BatteryPanel - Displays min/max voltage, cycle count, sample count Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>