feat(catalog): store furniture bundles as .hab instead of .nitro

Every bundle the CMS writes — upload, clone, sync, repair and the pet /
effect / figure importers — now lands as `<classname>.hab`, the extension
this deployment's renderer asks for. `.hab` and `.nitro` are the same
container, so an upload of either extension is accepted.

Resolution goes through one module, src/lib/furni/bundle-file.ts, so
nothing has to know the extension twice. Every existence check probes
`.hab` first and falls back to `.nitro`: the on-disk asset set is still
predominantly `.nitro`, and without the fallback Studio would report every
imported item as missing and the cleanup scan would classify 18k live
bundles as fake leftovers. Downloads are unchanged — Habbo's CDN and every
configured clone source still serve `.nitro`, so the conversion happens on
write, not on request.

Deliberately unchanged: the staged-attachment store in furni-attachment.ts
keys on a UUID and never reaches the client, so renaming it would break
in-flight recovery jobs.

Adds scripts/migrate-nitro-to-hab.ts to rename the existing asset set. It
refuses to run without --dry-run or --yes, never overwrites an existing
.hab, never deletes, and is idempotent.

Note: renderer-config.json lives outside this repo and was patched to
.hab separately; that file is served with a 30-day max-age, so returning
clients need a cms-client cache purge to pick the change up.

scripts/furni-diagnose-now.ts

@@ -1,9 +1,10 @@
 import "./load-env";
 import { createHash } from "node:crypto";
-import { existsSync, readdirSync, readFileSync, statSync } from "node:fs";
+import { readdirSync, readFileSync, statSync } from "node:fs";
 import path from "node:path";
 import { sql } from "drizzle-orm";
 import { CatalogItems, db, ItemsBase } from "@/lib/db";
+import { bundleExistsInDir } from "@/lib/furni/bundle-file";
 import { readFurniData } from "@/lib/services/furni-data";
 
 const ICON_DIR = path.join(
@@ -191,11 +192,10 @@ async function main(): Promise<void> {
 		);
 
 	let nitroMissing = 0;
-	const nitroSet = new Set(existsSync(NITRO_DIR) ? readdirSync(NITRO_DIR) : []);
 	for (const cls of catalogClasses) {
-		if (!nitroSet.has(`${cls}.nitro`)) nitroMissing++;
+		if (!bundleExistsInDir(NITRO_DIR, cls)) nitroMissing++;
 	}
-	console.log(`[5] catalog items without .nitro bundle: ${nitroMissing}`);
+	console.log(`[5] catalog items without a bundle on disk: ${nitroMissing}`);
 
 	await db.$client.end();
 	process.exit(0);