Auto-fix furni asset ownership after import

After each single or batch import, chown the swf/icon/nitro asset
directories and the FurnitureData.json folders to www-data:www-data so
nginx and the emulator can read newly written files. Best-effort and
non-blocking; the API response reports which folders were fixed.

src/lib/services/furni-data.ts

@@ -35,7 +35,7 @@ export async function getFurnitureDataPath(): Promise<string> {
 	return path.join(/*turbopackIgnore: true*/ process.cwd(), "public", relative);
 }
 
-async function getFurnitureDataWritePaths(): Promise<string[]> {
+export async function getFurnitureDataWritePaths(): Promise<string[]> {
 	const primary = await getFurnitureDataPath();
 	const configuredMirror =
 		(await siteSettings.get("furni_data_mirror_path", "")) ?? "";