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/photos/route.ts

@@ -2,8 +2,6 @@ import { count, desc } from "drizzle-orm";
 import { apiJson, pagination } from "@/lib/api";
 import { CameraWeb, db } from "@/lib/db";
 
-export const dynamic = "force-dynamic";
-
 /**
  * GET /api/photos — recent community photos (camera_web), newest first.
  * Mirrors the /photos page query. Returns id, userId, url and timestamp plus