New "Battery / Power" card shows mains vs battery, charge % with a severity- colored bar (only bites while on battery), the last alert level, and the configured warn/shutdown thresholds. van-battery now includes warn_levels + shutdown_level in /run/van-battery/state.json so the card stays self-describing instead of hardcoding the numbers. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>