add two decimal and add confirm dialog if press back button

lib/pages/profile/profile_currency_edit.dart

@@ -59,7 +59,11 @@ class _ProfileCurrencyEditState extends State<ProfileCurrencyEdit> {
               size: 35,
               color: primaryColor,
             ),
-            onPressed: () => Navigator.of(context).pop(),
+            onPressed: () {
+              showConfirmDialog(context, "back.button_confirm", () {
+                Navigator.of(context).pop();
+              });
+            },
           ),
         ),
         body: Column(