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/SubscriptionPlansManager.tsx

@@ -14,6 +14,7 @@ import {
   type SubscriptionPlan,
 } from "./api.js";
 import { Modal } from "./ui/Modal.js";
+import { currencyOptions } from "./lib/currencies.js";
 
 // Admin-only subscription PLAN catalog. Plans are admin-composed, versioned config the
 // operator sells from (so the operator never types a price). Editing a plan PUBLISHES A
@@ -348,7 +349,11 @@ export function SubscriptionPlansManager() {
               <label className="label">{t("plans.pricePer")}</label>
               <span className="flex items-center gap-2">
                 <input className="input w-28" value={form.priceMajor} inputMode="decimal" onChange={(e) => setForm((f) => f && { ...f, priceMajor: e.target.value })} placeholder="e.g. 800" />
-                <input className="input w-16" value={form.currency} onChange={(e) => setForm((f) => f && { ...f, currency: e.target.value })} />
+                <select className="input w-auto" value={form.currency} onChange={(e) => setForm((f) => f && { ...f, currency: e.target.value })}>
+                  {currencyOptions(form.currency).map((c) => (
+                    <option key={c} value={c}>{c}</option>
+                  ))}
+                </select>
                 <span className="text-[0.75rem] text-term-muted">/ {t(PERIOD_KEY[form.period])}</span>
               </span>
             </div>