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/api/media/[...path]/route.ts

@@ -4,8 +4,6 @@ import path from "node:path";
 import { NextResponse } from "next/server";
 import { MEDIA_ROOT, resolveMediaPath } from "@/lib/media-storage";
 
-export const dynamic = "force-dynamic";
-
 const ALLOWED_EXT = [".png", ".jpg", ".jpeg", ".gif", ".webp", ".svg", ".bmp"];
 
 export async function GET(

src/app/api/media/route.ts

@@ -3,8 +3,6 @@ import { resolve } from "node:path";
 import { NextResponse } from "next/server";
 import { MEDIA_ROOT } from "@/lib/media-storage";
 
-export const dynamic = "force-dynamic";
-
 export async function GET() {
 	const dir = MEDIA_ROOT;
 	// eslint-disable-next-line security/detect-non-literal-fs-filename