Show common currencies first in dropdowns and default to USD in install wizard

Currency dropdowns now display the most-traded currencies (USD, EUR, GBP,
JPY, CAD, AUD, CHF, CNY, INR, BRL) at the top, followed by the rest
alphabetically. The install wizard defaults to USD instead of EUR and
formats currency names as "USD - US Dollar" for consistency with the
rest of the app.

app/Models/Currency.php

@@ -9,6 +9,11 @@ class Currency extends Model
 {
     use HasFactory;
 
+    public const COMMON_CURRENCY_CODES = [
+        'USD', 'EUR', 'GBP', 'JPY', 'CAD',
+        'AUD', 'CHF', 'CNY', 'INR', 'BRL',
+    ];
+
     protected $guarded = [
         'id',
     ];