feat: speed up admin clone import and enable Cache Components

- Clone import: defer FurnitureData.json writes and append all entries in a
  single batched write instead of one read-modify-write per item, removing
  the main serialization bottleneck for large batches.
- Clone import: raise SSE batch concurrency cap from 5 to 10 and bump the
  clone client/route default from 2 to 6.
- Add a flush hook to runSseBatch so callers can batch deferred work before
  batch_complete is emitted, and surface flush errors as an error event.
- Enable Next.js Cache Components (instant: false opt-out) and silence the
  related build warnings in next.config.ts.
- Switch isomorphic-dompurify to dompurify and refresh dependencies.

src/app/admin/catalog/[id]/page.tsx

@@ -9,6 +9,10 @@ import { loadCatalogItemsData } from "@/lib/services/catalog-items-loader";
 import { getAncestors } from "@/lib/services/catalog-tree";
 import { CatalogDetailTabs } from "./catalog-detail-tabs";
 
+// TODO: Cache Components adoption. Refactor this route so this opt-out can be removed.
+// See: https://nextjs.org/docs/app/guides/migrating-to-cache-components
+export const instant = false;
+
 export default async function CatalogEditPage({
 	params,
 }: {

src/app/admin/catalog/builder-club/[id]/page.tsx

@@ -4,6 +4,10 @@ import { CatalogItemsBc, CatalogPagesBc, db } from "@/lib/db";
 import { canAccess, getAdminContext, PERMS } from "@/lib/permissions";
 import { BcPageDetail } from "../bc-manager";
 
+// TODO: Cache Components adoption. Refactor this route so this opt-out can be removed.
+// See: https://nextjs.org/docs/app/guides/migrating-to-cache-components
+export const instant = false;
+
 export default async function BcPageDetailPage({
 	params: paramsPromise,
 }: {

src/app/admin/catalog/builder-club/page.tsx

@@ -1,5 +1,9 @@
 import { redirect } from "next/navigation";
 
+// TODO: Cache Components adoption. Refactor this route so this opt-out can be removed.
+// See: https://nextjs.org/docs/app/guides/migrating-to-cache-components
+export const instant = false;
+
 export default function BuilderClubPage() {
 	redirect("/admin/catalog?catalog=bc");
 }

src/app/admin/catalog/page.tsx

@@ -31,6 +31,10 @@ import { CatalogManagerDialog } from "./catalog-manager-dialog-wrapper";
 import { CatalogTable } from "./catalog-table";
 import { CatalogViewToggle } from "./catalog-view-toggle";
 
+// TODO: Cache Components adoption. Refactor this route so this opt-out can be removed.
+// See: https://nextjs.org/docs/app/guides/migrating-to-cache-components
+export const instant = false;
+
 async function rawRows<T>(query: ReturnType<typeof sql>): Promise<T[]> {
 	const [rows] = (await db.execute(query)) as unknown as [T[], unknown];
 	return rows ?? [];