perf(studio): cache furni imports and virtualize the furniture grid

- Add TTL-based caching for local index lookup, furnidata classnames,
  catalog id set, nitro file presence and import stats
- Invalidate caches after furnace single/batch/clone imports
- Rewrite batch progress with elapsed time, rate and verification chips
- Virtualize the grid with @tanstack/react-virtual and replace the
  Load more button with infinite scroll via an IntersectionObserver

src/app/api/admin/import/clone/batch/route.ts

@@ -21,6 +21,7 @@ import {
 	syncAssetsToGamedataBundle,
 	verifyAndFixInteractionModesCount,
 } from "@/lib/services/furni-import";
+import { clearFurniImportCache } from "@/lib/services/furni-import-cache";
 import { runSseBatch } from "@/lib/services/import/core/sse-batch";
 import { rcon } from "@/lib/services/rcon";
 
@@ -179,6 +180,9 @@ export const POST = withAdmin(
 				} catch {
 					/* best effort — post-import consolidation is non-fatal */
 				}
+
+				// New items + files landed — drop caches so the Studio refresh is fresh.
+				clearFurniImportCache();
 			},
 		});
 	},