2f8a8a2b77
- New CapacityTest model (battery_id FK CASCADE, mah, date, notes) - DB migration: create capacity_test table, migrate existing single-test data - Two new routes: add and delete capacity test records - Battery.tested_capacity_mah/tested_date kept in sync with latest test so dashboard display requires no changes - Battery detail: Capacity History card with sortable table, health % per reading, and a canvas line chart (shown when >= 2 records) - Chart uses CSS variables for colors — works in light and dark mode - Remove tested_capacity_mah/tested_date from Edit Details form - 3 new acceptance tests (48 total)