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.

src/lib/furni/classname.test.ts

@@ -1,14 +1,17 @@
 import { describe, expect, it } from "vitest";
 import {
 	getBaseClassname,
+	getBundleFileName,
 	getHabboCdnIconUrl,
 	getIconFileName,
+	getLocalBundleFileNames,
 	getLocalIconUrl,
 	getNitroFileName,
 	getSafeClassnameStem,
 	getSwfFileName,
 	isValidClassname,
 	normalizeClassname,
+	SOURCE_BUNDLE_EXT,
 } from "./classname";
 
 describe("getBaseClassname", () => {
@@ -36,8 +39,19 @@ describe("file name helpers", () => {
 	it("builds swf file names from the base classname", () => {
 		expect(getSwfFileName("sofa_blue*")).toBe("sofa_blue.swf");
 	});
-	it("builds nitro file names from the base classname", () => {
-		expect(getNitroFileName("sofa_blue*")).toBe("sofa_blue.nitro");
+	it("builds the primary (`.hab`) bundle name from the base classname", () => {
+		expect(getNitroFileName("sofa_blue*")).toBe("sofa_blue.hab");
+	});
+	it("offers `.hab` first and keeps legacy `.nitro` resolvable", () => {
+		expect(getLocalBundleFileNames("sofa_blue*")).toEqual([
+			"sofa_blue.hab",
+			"sofa_blue.nitro",
+		]);
+	});
+	it("builds a bundle name for an explicit extension", () => {
+		expect(getBundleFileName("sofa_blue*", SOURCE_BUNDLE_EXT)).toBe(
+			"sofa_blue.nitro",
+		);
 	});
 });