Replace standalone catalog editor with the unified Visual Catalog studio

Make /admin/catalog a full-screen catalog studio that replaces the old
listing plus separate [id]/builder-club detail pages:

- Embed CatalogManagerWorkspace on /admin/catalog with a Normal/Builder
  Club toggle, Catalog Sync status, packages (normal), Organize imports
  and a diagnostics link to /admin/studio/maintenance.
- Manage BC items directly in the studio Items tab (new BcItemsEditor,
  CRUD via existing bc actions; /api/admin/catalog/items now serves BC).
- Inline editor: add pageTextTeaser field for both catalogs and remove
  the legacy full-editor links.
- Remove the 'Open full editor' context action from the tree.
- Move catalog-items-table (dir + barrel) and catalog-translate-tab out
  of the app route into src/components/admin/catalog and update all
  importers.
- Keep /admin/catalog/[id], builder-club/[id] and /admin/catalog/maintenance
  as redirects into the new studio; consolidate maintenance panels into
  /admin/studio/maintenance and point the nav item there.
- Delete the old listing/table/tabs/forms and the standalone bc-manager.

src/app/admin/catalog/maintenance/page.tsx

@@ -1,7 +1,4 @@
 import { redirect } from "next/navigation";
-import { getTranslations } from "next-intl/server";
-import { CatalogIntegrityPanel } from "@/components/admin/catalog/catalog-integrity-panel";
-import { CatalogMaintenancePanel } from "@/components/admin/catalog/catalog-maintenance-panel";
 import { canAccess, getAdminContext, PERMS } from "@/lib/permissions";
 
 export default async function CatalogMaintenancePage() {
@@ -9,27 +6,5 @@ export default async function CatalogMaintenancePage() {
 	if (!canAccess(permissions, PERMS.CATALOG_VIEW, session.user.rank)) {
 		redirect("/admin");
 	}
-
-	const canRepair = canAccess(
-		permissions,
-		PERMS.CATALOG_EDIT,
-		session.user.rank,
-	);
-	const t = await getTranslations("pages.admin.catalog.integrity");
-	return (
-		<div className="space-y-6">
-			<CatalogIntegrityPanel canRepair={canRepair} />
-			{canRepair && (
-				<details className="rounded-xl border p-4">
-					<summary className="cursor-pointer font-medium">
-						{t("legacyTitle")}
-					</summary>
-					<p className="mt-3 text-sm text-muted-foreground">
-						{t("legacyHint")}
-					</p>
-					<CatalogMaintenancePanel />
-				</details>
-			)}
-		</div>
-	);
+	redirect("/admin/studio/maintenance");
 }