feat: add phx-debounce to amount input for real-time validation

- Debounce validation to 300ms for better UX
- Ash will automatically validate Decimal format
- Provides immediate feedback on invalid input

lib/mv_web/live/membership_fee_type_live/form.ex

@@ -46,6 +46,7 @@ defmodule MvWeb.MembershipFeeTypeLive.Form do
           label={gettext("Amount")}
           step="0.01"
           min="0"
+          phx-debounce="300"
           required
         />