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.

e2e/ui/attachment-recovery.spec.ts

@@ -2,7 +2,7 @@ import { expect, test } from "@playwright/test";
 
 const attachmentId = "bbbbbbbb-bbbb-4bbb-8bbb-bbbbbbbbbbbb";
 const file = {
-	name: "fixture_chair.nitro",
+	name: "fixture_chair.hab",
 	mimeType: "application/octet-stream",
 	buffer: Buffer.from("isolated upload fixture"),
 };
@@ -23,7 +23,7 @@ test("attachment upload and double-click resume send one retry and refresh histo
 		expect(route.request().postData()).toContain('name="classname"');
 		expect(route.request().postData()).toContain("fixture_chair");
 		expect(route.request().postData()).toContain(
-			'filename="fixture_chair.nitro"',
+			'filename="fixture_chair.hab"',
 		);
 		await route.fulfill({ json: { ok: true, attachmentId } });
 	});
@@ -38,7 +38,7 @@ test("attachment upload and double-click resume send one retry and refresh histo
 		await new Promise((resolve) => setTimeout(resolve, 150));
 		await route.fulfill({ json: { ok: true } });
 	});
-	await page.getByLabel("Choose the original .nitro file").setInputFiles(file);
+	await page.getByLabel("Choose the original .hab file").setInputFiles(file);
 	await expect(
 		page.getByText("Matching original file attached", { exact: true }),
 	).toBeVisible();
@@ -94,9 +94,7 @@ for (const scenario of [
 					})
 				: route.abort("failed"),
 		);
-		await page
-			.getByLabel("Choose the original .nitro file")
-			.setInputFiles(file);
+		await page.getByLabel("Choose the original .hab file").setInputFiles(file);
 		await expect(page.getByRole("alert")).toContainText(scenario.message);
 		await expect(
 			page.getByRole("button", {