Multiple methods wrote directly to os.Stdout instead of using the injectable
v.Stdout writer, breaking the TestVaultik testing infrastructure and making
output impossible to capture or redirect.
Fixed in: ListSnapshots, PurgeSnapshots, VerifySnapshotWithOptions,
PruneBlobs, outputPruneBlobsJSON, outputRemoveJSON, ShowInfo, RemoteInfo.
CompressStream had both a defer w.Close() and an explicit w.Close() call,
causing the compressor and encryptor to be closed twice. The second close
on the zstd encoder returns an error, and the age encryptor may write
duplicate finalization bytes, potentially corrupting the output stream.
Use a closed flag to prevent the deferred close from running after the
explicit close succeeds.