feat: add currency for articles (#834)

Co-authored-by: Jakob Wennberg <jakob.wennberg@gmail.com>

messages/en.json

@@ -4363,6 +4363,8 @@
     "revenue_account_hint": "Leave empty to derive the account automatically from the VAT rate.",
     "cost_price_label": "Cost price",
     "cost_price_hint": "Margin display only, never posted.",
+    "currency_label": "Currency",
+    "currency_hint": "Pre-fills a new invoice's currency when the article is added.",
     "ean_label": "EAN/barcode",
     "ean_placeholder": "e.g. 7350000000000",
     "housework_label": "ROT/RUT",

messages/sv.json

@@ -4363,6 +4363,8 @@
     "revenue_account_hint": "Lämna tomt för att härleda kontot automatiskt utifrån momsen.",
     "cost_price_label": "Inköpspris",
     "cost_price_hint": "Endast för marginalberäkning, bokförs aldrig.",
+    "currency_label": "Valuta",
+    "currency_hint": "Förifyller en ny fakturas valuta när artikeln läggs till.",
     "ean_label": "EAN/streckkod",
     "ean_placeholder": "t.ex. 7350000000000",
     "housework_label": "ROT/RUT",