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/users/[id]/edit/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;
+
 /**
  * Legacy URL — the canonical edit UI lives at /admin/users/edit/[id]
  * and is gated by PERMS.USERS_EDIT.

src/app/admin/users/[id]/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;
+
 /** Legacy route — redirects to /admin/users/show/[id] */
 export default async function UserLegacyPage({
 	params,

src/app/admin/users/edit/[id]/page.tsx

@@ -14,6 +14,10 @@ import { UserEditForm } from "../../[id]/user-edit-form";
 import { UserQuickActions } from "../../[id]/user-quick-actions";
 import { UserRooms } from "../../[id]/user-rooms";
 
+// 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 UserEditPage({
 	params,
 }: {

src/app/admin/users/multi-accounts/page.tsx

@@ -9,6 +9,10 @@ import { Badge } from "@/components/ui/badge";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
 import { canAccess, getAdminContext, PERMS } from "@/lib/permissions";
 
+// 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 MultiAccountsPage({
 	searchParams,
 }: {

src/app/admin/users/page.tsx

@@ -8,6 +8,10 @@ import { canAccess, PERMS } from "@/lib/permissions";
 import { CreateUserDialog } from "./_components/create-user-dialog";
 import { UsersTable } from "./users-table";
 
+// 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 UsersPage({
 	params: paramsPromise,
 	searchParams,

src/app/admin/users/show/[id]/page.tsx

@@ -13,6 +13,10 @@ import { UserActivityLog } from "../../[id]/user-activity-log";
 import { UserQuickActions } from "../../[id]/user-quick-actions";
 import { UserRooms } from "../../[id]/user-rooms";
 
+// 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 UserShowPage({
 	params,
 }: {