59b232c5fc
7 Tasks (TDD, atomic commits):
1. unitFamily + Unit-Tests
2. consolidate + Tests fuer alle Edge-Cases
3. formatQuantity auf toLocaleString('de-DE', ...)
4. Migration 015 — Check-Keys auf Family
5. listShoppingList konsolidiert via TS-side grouping
6. clearCheckedItems + toggleCheck auf Family-Key
7. E2E-Smoke im Dev-Deployment
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>