feat(web): currency becomes a closed select (ALL / EUR / USD)

Currency was free text in the tariff editor (composer page + lab draft
modal — shared form) and the subscription plan editor; a typo could
publish an unknown code onto immutable versions. Both now offer a closed
select from lib/currencies.ts. An out-of-set code already stored on an
old record is appended as an extra option so it displays + round-trips
unchanged. Blank tariff form defaults to ALL (was EUR) — the site's
actual currency.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

apps/web/src/TariffEditorForm.tsx

@@ -1,4 +1,5 @@
 import { useTranslation } from "react-i18next";
+import { currencyOptions } from "./lib/currencies.js";
 import {
   isTariffV2,
   type TariffBlock,
@@ -101,7 +102,7 @@ function emptyTier(): TierForm {
 
 export function emptyForm(): FormState {
   return {
-    currency: "EUR",
+    currency: "ALL",
     gracePeriodEntryMin: "15",
     incrementMin: "60",
     lostTicket: "20.00",
@@ -339,7 +340,11 @@ export function TariffEditorForm({
     <div>
       <div className="card card-body grid grid-cols-[max-content_1fr] items-center gap-x-4 gap-y-2">
         <label className="label">{t("tariff.currency")}</label>
-        <input className="input w-24" value={form.currency} onChange={(e) => set("currency", e.target.value)} maxLength={3} />
+        <select className="input w-24" value={form.currency} onChange={(e) => set("currency", e.target.value)}>
+          {currencyOptions(form.currency).map((c) => (
+            <option key={c} value={c}>{c}</option>
+          ))}
+        </select>
         <label className="label">{t("tariff.freeEntryGrace")}</label>
         <input className="input w-32" value={form.gracePeriodEntryMin} onChange={(e) => set("gracePeriodEntryMin", e.target.value)} />
         <label className="label">{t("tariff.billingIncrement")}</label>