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/services/clone-import.test.ts

@@ -168,7 +168,7 @@ describe("clone-import", () => {
 		expect(r.skipped).toBe(true);
 	});
 
-	it("rolls back: unlinks .nitro and icon, skips FurnitureData when items_base INSERT rejects", async () => {
+	it("rolls back: unlinks the bundle and icon, skips FurnitureData when items_base INSERT rejects", async () => {
 		const warn = vi.spyOn(console, "warn").mockImplementation(() => {});
 		downloadFile.mockReset();
 		downloadFile.mockResolvedValue({ ok: true, size: 200 });
@@ -190,9 +190,9 @@ describe("clone-import", () => {
 				entry: { ...ENTRY, itemType: "s" },
 			});
 
-			// (a) .nitro must be unlinked.
+			// (a) the bundle (`.hab`) must be unlinked.
 			expect(fsUnlink).toHaveBeenCalledWith(
-				expect.stringContaining("bc_sofa.nitro"),
+				expect.stringContaining("bc_sofa.hab"),
 			);
 			// (b) icon must also be unlinked.
 			expect(fsUnlink).toHaveBeenCalledWith(