SeaweedFS: Hard-coded SSH host key can be presented by certain standalone SFTP Helm deployments

SeaweedFS is a distributed storage system for files and blobs. From 4.0.388 until 4.41, the SFTP Helm chart embedded one unencrypted Ed25519 private host key in k8s/charts/seaweedfs/templates/sftp/sftp-secret.yaml as stringData.seaweedfs_sftp_ssh_private_key. A standalone deployment presented that public key when sftp.enabled and sftp.enableAuth were true, sftp.existingConfigSecret was not supplied, the legacy sftp.sshPrivateKey path remained selected, a valid config-ssh Secret allowed startup, and hostKeysFolder did not provide a later Ed25519 signer. An attacker able to redirect or intercept client traffic could impersonate that SFTP endpoint to clients that trusted the published host identity, exposing password credentials or data sent to the rogue endpoint. Default all-in-one and non-authenticated standalone paths did not load the key. This issue is fixed in version 4.41.