39b52a3fa4
- base.html: add CSS/HTML/JS for styled in-app confirmation modal (dark-mode compatible via CSS vars) - device_list, battery_detail: convert onsubmit confirm() to declarative data-confirm attributes - dashboard: convert bulk Delete/Install buttons to use modal helpers (submitWithAction pattern) - app.py: pass brand_counts dict to battery_add template - battery_add.html: show live "Will create: Brand 001 → Brand 003" preview as brand/quantity change - tests: add two tests covering brand_counts server-side rendering