downloadBedrockRelay
public MagmaguyRspClient.RelayDownloadResult downloadBedrockRelay(String networkKeyHash, String backendId, String kind, File dest)
Download a relay entry to dest. The path is keyed by networkKeyHash (the same 32-char sha256 prefix the hoster stores under) rather than the raw key — the GET URL would otherwise leak the network identity in access logs.
Return
an explicit authoritative result. Transport/server/envelope failures throw so callers can retain their last-good cached copy; only NOT_FOUND authorises deletion.