feat: per-ingredient category selection for shopping list transfer (closes #33)

When adding ingredients in the meal editor, each ingredient now has a
category dropdown. Categories are stored on the ingredient and applied
automatically when transferring to the shopping list, so items appear
pre-grouped by category without manual re-sorting.

public/locales/hi.json

@@ -226,6 +226,8 @@
     "addIngredient": "सामग्री जोड़ें",
     "ingredientNamePlaceholder": "सामग्री",
     "ingredientQtyPlaceholder": "मात्रा",
+    "ingredientCategoryLabel": "श्रेणी",
+    "ingredientCategoryDefault": "विविध",
     "removeIngredient": "सामग्री हटाएं",
     "transferLabel": "सामग्री खरीदारी सूची में जोड़ें",
     "transferNow": "अभी जोड़ें",
@@ -596,4 +598,4 @@
     "unitMonth": "माह",
     "unitMonths": "माह"
   }
-}
+}