Admin: gestión de foros (categorías y foros)

- lib/admin-forum.ts: listCategoriesWithForums, createCategory/deleteCategory
  (solo si vacía), createForum/deleteForum (borrado lógico), setForumVisibility.
- API: /api/admin/forum(+/[id] DELETE/PATCH visibilidad) y
  /api/admin/forum/category(+/[id]) (403 sin admin).
- UI: /admin/forum (AdminForumManager) — alta de categorías, alta/borrado de foros
  por categoría, mostrar/ocultar; tarjeta "Gestionar foros" en el índice del admin.
- i18n es/en (Admin): 13 claves nuevas.

Verificado: build OK, /admin/forum 307->login, APIs 403 sin admin.

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

web-next/app/[locale]/admin/forum/page.tsx

@@ -0,0 +1,24 @@
+import { getTranslations, setRequestLocale } from 'next-intl/server'
+import { redirect } from '@/i18n/navigation'
+import { getSession } from '@/lib/session'
+import { isAdmin } from '@/lib/admin'
+import { listCategoriesWithForums } from '@/lib/admin-forum'
+import { AdminForumManager } from '@/components/AdminForumManager'
+
+export const dynamic = 'force-dynamic'
+
+export default async function AdminForumPage({ params }: { params: Promise<{ locale: string }> }) {
+  const { locale } = await params
+  setRequestLocale(locale)
+  const t = await getTranslations('Admin')
+  const session = await getSession()
+  if (!session.bnetId) redirect({ href: '/login', locale })
+  if (!(await isAdmin(session))) redirect({ href: '/', locale })
+  const groups = await listCategoriesWithForums()
+  return (
+    <main className="mx-auto max-w-3xl px-4 py-8">
+      <h1 className="mb-6 text-2xl font-bold text-amber-500">{t('forum')}</h1>
+      <AdminForumManager initial={groups} />
+    </main>
+  )
+}