feat: generic shopping names — group products by shopping_name

- Add shopping_name column to products table
- Add computeShoppingName() PHP auto-assign function:
  * Curated keyword map: all salumi/cold cuts → 'Affettato'
  * Bring! catalog back-translation: 'Latte di Montagna' → 'Latte'
  * Fallback: first significant token capitalized
- Migrate all 210 existing products with auto-computed shopping_name
- saveProduct() auto-computes shopping_name on every create/update
- smartShopping() groups items by shopping_name: most urgent item is
  representative, others listed as variants (e.g. 'Affettato' shows
  Mortadella, Speck, Nduja, Salame, Prosciutto, Schinkenspeck as one row)
- _productOnBring() also checks shopping_name for Bring! match detection
- addToInventory auto-remove: uses shopping_name-based Bring! key
- useFromInventory auto-add: sends shopping_name to Bring! (not raw name),
  specific product name goes into specification field
- Frontend renderSmartItem: shows shopping_name as title, specific
  product name(s) in italic subtitle line below
- _syncOnBringFlags: matches on both name and shopping_name

assets/css/style.css

@@ -1963,6 +1963,14 @@ body {
     line-height: 1.3;
 }
 
+.smart-item-specific {
+    font-size: 0.73rem;
+    color: var(--text-muted);
+    margin-top: 1px;
+    line-height: 1.3;
+    font-style: italic;
+}
+
 .smart-brand {
     font-weight: 400;
     color: var(--text-muted);