Send all available hostname sources (ComputerName, LocalHostName,
HostName, os.Hostname) in the metadata map when provisioning.
This allows the API to detect and repair generic hostnames like
'Mac' by picking the best available source server-side.
Belt and suspenders: preferredHostname() picks the right one
client-side, but metadata gives the API a second chance.
macOS Sequoia with Private Wi-Fi Address enabled causes os.Hostname()
to return generic names like "Mac.lan" from DHCP instead of the real
computer name. The /utility provisioning endpoint sends this raw,
resulting in devices named "Mac-lan" in the dashboard.
Fallback chain: ComputerName → LocalHostName → os.Hostname()
LocalHostName can also be affected by DHCP. ComputerName is the
user-set display name from System Settings, fully immune to network state.
Codescribe