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/effect-import.ts

@@ -1,4 +1,9 @@
 import { existsSync, promises as fs } from "node:fs";
+import {
+	bundleExistsInDir,
+	bundleWritePathInDir,
+	existingBundlePaths,
+} from "@/lib/furni/bundle-file";
 import {
 	listOfficialEffects,
 	resolveEffectSwfUrl,
@@ -63,10 +68,12 @@ export async function ensureEffectDirs(): Promise<void> {
 	);
 }
 
+// Imports write `.hab`, the extension the client requests; a bundle still on
+// disk as legacy `.nitro` keeps counting as present.
 async function nitroPathFor(lib: string): Promise<string> {
-	return getRuntimePath(
+	return bundleWritePathInDir(
 		/*turbopackIgnore: true*/ await getEffectNitroDir(),
-		`${lib}.nitro`,
+		lib,
 	);
 }
 
@@ -146,11 +153,15 @@ export async function deleteImportedEffect(
 	const removed = await removeEffect(idOrLib);
 	let deletedFile = false;
 	if (entry) {
-		const p = await nitroPathFor(entry.lib);
-		if (existsSync(/*turbopackIgnore: true*/ p)) {
+		// Clear both conventions so a re-import cannot resurrect a stale bundle.
+		const paths = existingBundlePaths(
+			[/*turbopackIgnore: true*/ await getEffectNitroDir()],
+			entry.lib,
+		);
+		for (const p of paths) {
 			await fs.unlink(/*turbopackIgnore: true*/ p).catch(() => {});
-			deletedFile = true;
 		}
+		deletedFile = paths.length > 0;
 	}
 	return { removed, deletedFile };
 }
@@ -169,9 +180,7 @@ export async function getEffectList(search: string): Promise<EffectListItem[]> {
 	const merged = base.map((e) => ({
 		...e,
 		present: localByLib.has(e.lib),
-		nitroExists: existsSync(
-			/*turbopackIgnore: true*/ getRuntimePath(nitroDir, `${e.lib}.nitro`),
-		),
+		nitroExists: bundleExistsInDir(/*turbopackIgnore: true*/ nitroDir, e.lib),
 	}));
 	return term
 		? merged.filter(