Añade gold y transfer: patrón de pago unificado con fulfill + metadata

- lib/stripe.ts: createCheckoutSession acepta metadata; claimPaidCheckout la
  recupera de la sesión Stripe y la devuelve.
- lib/paid-services.ts: config unificado con fulfill(character, meta) + extraFields.
  gold -> UPDATE characters money (BD directa, no SOAP), transfer -> SOAP
  .char changeaccount. Los 5 simples usan soapFulfill.
- checkout [service]: lee extraFields -> metadata, precio depende de metadata (gold),
  valida precio>0. service-success llama cfg.fulfill(name, metadata).
- prices.ts: getTransferPrice, getGoldOptions/goldPriceFor (home_goldprice).
- GoldForm (personaje + cantidad) y TransferForm (personaje + destino); páginas
  /gold y /transfer. Catálogos Paid.gold/transfer.

Verificado: /gold /transfer redirigen a login, checkout 401 sin sesión, home OK.
NOTA: transfer no valida aún el token de seguridad ni reglas AC (nivel>=55, DK).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web-next/app/[locale]/transfer/page.tsx

@@ -0,0 +1,26 @@
+import { getTranslations, setRequestLocale } from 'next-intl/server'
+import { redirect } from '@/i18n/navigation'
+import { getSession } from '@/lib/session'
+import { getGameCharacters } from '@/lib/characters'
+import { getTransferPrice } from '@/lib/prices'
+import { TransferForm } from '@/components/TransferForm'
+
+export const dynamic = 'force-dynamic'
+
+export default async function TransferPage({ params }: { params: Promise<{ locale: string }> }) {
+  const { locale } = await params
+  setRequestLocale(locale)
+  const t = await getTranslations('Paid')
+  const session = await getSession()
+  if (!session.bnetId) redirect({ href: '/login', locale })
+  if (!session.username) redirect({ href: '/select-account', locale })
+
+  const [chars, price] = await Promise.all([getGameCharacters(session.accountId!), getTransferPrice()])
+
+  return (
+    <main className="mx-auto max-w-3xl px-4 py-8">
+      <h1 className="mb-6 text-center text-2xl font-bold text-amber-500">{t('transfer.title')}</h1>
+      <TransferForm characters={chars.map((c) => c.name)} price={price} />
+    </main>
+  )
+}