fix: decode UTF-8 before encoding to another encoding

src/servers/allnet/middleware/dfi.ts

@@ -47,6 +47,7 @@ export const DFIRequestResponse: (mustUseDfi: boolean) => RequestHandler = (must
 		req.safeBody = req.body as Record<string, unknown>;
 
 		const transformers: Array<NodeJS.ReadWriteStream> = [
+			iconv.decodeStream("utf-8"),
 			iconv.encodeStream(req.body.encode ?? "EUC-JP"),
 		];