feat(front-end): calculator improvements

frontend/src/assets/i18n/de.json

@@ -402,6 +402,7 @@
     "SETUP_FEE": "Einrichtungskosten",
     "TOTAL": "Gesamt",
     "QTY": "Menge",
+    "MATERIAL": "Material",
     "PER_PIECE": "pro Stück",
     "SHIPPING": "Versand (CH)",
     "PREVIEW_LOADING": "3D-Vorschau wird geladen...",

frontend/src/assets/i18n/en.json

@@ -402,6 +402,7 @@
     "SETUP_FEE": "Setup Fee",
     "TOTAL": "Total",
     "QTY": "Qty",
+    "MATERIAL": "Material",
     "PER_PIECE": "per piece",
     "SHIPPING": "Shipping",
     "PREVIEW_LOADING": "Loading 3D preview...",

frontend/src/assets/i18n/fr.json

@@ -459,6 +459,7 @@
     "SETUP_FEE": "Coût de setup",
     "TOTAL": "Total",
     "QTY": "Qté",
+    "MATERIAL": "Matériau",
     "PER_PIECE": "par pièce",
     "SHIPPING": "Expédition (CH)",
     "PREVIEW_LOADING": "Chargement de l'aperçu 3D...",

frontend/src/assets/i18n/it.json

@@ -459,6 +459,7 @@
     "SETUP_FEE": "Costo di Avvio",
     "TOTAL": "Totale",
     "QTY": "Qtà",
+    "MATERIAL": "Materiale",
     "PER_PIECE": "al pezzo",
     "SHIPPING": "Spedizione (CH)",
     "PREVIEW_LOADING": "Caricamento anteprima 3D...",