Make the «Currency» field currency-selectable per field instance

[alexanderbuergin]

The problem

Craft’s «Currency» field is locked to one currency set in the field settings.
If the same field is reused in several layouts, every entry is forced to use that single currency.

Desired behaviour

• In the field settings choose between two modes:
  1. Single currency – works exactly as today.
  2. Selectable currencies – define one or more ISO-4217 codes (e.g. USD, EUR, CHF).
• When mode 2 is active the field’s UI shows a currency dropdown beside the amount input.
• The chosen currency code is stored together with the numeric value.
• Twig, GraphQL, and Element APIs expose both value and currency.

Why it matters

Many sites need prices in several currencies within the same content.
Duplicating the field for each currency clutters the schema and breaks the reuse principle.

Benefits

• Editors pick the right currency per entry or Matrix block—no extra fields.
• Developers keep tidy field sets and can still define a default.
• Fully backward-compatible: existing fields remain in single-currency mode.

Happy to test or supply additional details if helpful. Thanks for considering!