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/upload-import.ts

@@ -1,8 +1,12 @@
-import { existsSync, promises as fs } from "node:fs";
+import { promises as fs } from "node:fs";
 import path from "node:path";
 import { eq, sql } from "drizzle-orm";
 import { db, ItemsBase, queryRows } from "@/lib/db";
 import { autoDetectInteraction } from "@/lib/furni/auto-interaction";
+import {
+	bundleWritePathInDir,
+	resolveBundleInDir,
+} from "@/lib/furni/bundle-file";
 import { logServerError } from "@/lib/server-log";
 import { getFurniAssetWriteTargets } from "@/lib/services/furni-asset-dirs";
 import { appendFurniEntry, buildFurniEntry } from "@/lib/services/furni-data";
@@ -293,26 +297,35 @@ export async function uploadSingleFurni(params: {
 		if (!isLosslessWebp(parsed.texture))
 			warnings.push("texture converted to WebP Lossless");
 	} catch {
-		return { ok: false, classname, warnings, error: "invalid .nitro bundle" };
+		return { ok: false, classname, warnings, error: "invalid bundle" };
 	}
 
 	await ensureDirectories();
 	const assetTargets = await getFurniAssetWriteTargets();
 	const { iconDir, nitroDir } = assetTargets;
 
-	const nitroFileName = `${classname}.nitro`;
-	const nitroPath = getRuntimePath(
+	// Bundles are stored as `<classname>.hab` — the extension this deployment's
+	// client requests. The uploaded file may arrive named `.hab` or `.nitro`;
+	// parsing above is format-based, so both are the same bundle. A legacy
+	// `.nitro` left on disk still counts as a collision, otherwise the item
+	// would end up served by whichever the client happens to ask for first.
+	const existingBundle = resolveBundleInDir(
 		/*turbopackIgnore: true*/ nitroDir,
-		nitroFileName,
+		classname,
 	);
-	if (existsSync(nitroPath)) {
+	if (existingBundle) {
 		return {
 			ok: false,
 			classname,
 			warnings,
-			error: ".nitro file already exists on disk",
+			error: `${path.basename(existingBundle)} already exists on disk`,
 		};
 	}
+	const nitroFileName = path.basename(bundleWritePathInDir("", classname));
+	const nitroPath = bundleWritePathInDir(
+		/*turbopackIgnore: true*/ nitroDir,
+		classname,
+	);
 	await fs.writeFile(nitroPath, storedNitro);
 
 	let iconFileName: string | null = null;