virtainer-guest-agent 0.3.0

First release with Windows guest support (Windows Server 2019, 2022 and
2025, and Windows 11 IoT Enterprise LTSC). On Windows the agent runs as a
LocalSystem service that speaks QGA to the host over vsock port 100 through
virtio-win's viosock provider, and provisions the guest from a FAT12 seed:
host name, network, accounts and SSH keys, optionally disabling the
built-in Administrator. The Linux agent behaves as in 0.2.1.

• Windows: a LocalSystem service serving the session, identity, time and
  power, network-interface and guest-exec commands listed in the README,
  with the same hybrid vsock handshake and framing as on Linux.
• Windows: provisioning from a FAT12 seed read without mounting it. The seed
  is checked against a strict schema, and per-instance checkpoints let a
  restart resume where it stopped. It sets the host name, network, time
  zone, accounts and SSH keys. The seed can also stage an agent update,
  kept with a backup to roll back to.
• Windows: admin.disable_builtin in the seed disables the built-in
  Administrator once the requested administrator exists. The account is
  found by SID, so a renamed or localized one is covered too.
• Windows: an interface that already has DHCP and a lease keeps it during
  network provisioning instead of falling back to APIPA.
• Windows: specialize sets only the hostname. Networking now runs in the
  service phase before accounts, because the network stack's RPC services are
  not available during specialize.
• Windows: accepted vsock connections are no longer switched with FIONBIO,
  which left viosock sockets non-blocking and made the agent drop connections
  that had no data pending. The listener stays blocking and is polled with a
  timeout so a service stop is still noticed.
• Windows: an existing read-only administrators_authorized_keys (or any other
  file the agent rewrites) no longer blocks provisioning.
• Windows: a failed PowerShell step records its error category, ID and message
  (administrator password removed, 300 characters at most) instead of only an
  exit status.

Assets

• virtainer-guest-agent-0.3.0-x86_64-linux: the static Linux binary.
• virtainer-guest-agent-0.3.0.iso: the read-only agent drive (label VIRTGA) for the
  ISO + boothook delivery described in the README.
• virtainer-guest-agent.exe: the Windows x86_64 service executable; see the README
  for installing the service and the specialize entry.
• SHA256SUMS: verify with sha256sum -c SHA256SUMS before you give any of them to a guest.