DesktopAppInstaller on this host returns 0x8a15000f with an empty
winget index; source reset does not recover it. Fetch MinGit and the
go.dev windows-amd64 zip into LOCALAPPDATA instead.
0x8a15000f ("Data required by the source is missing") aborts Git.Git /
GoLang.Go install on a virgin DesktopAppInstaller cache, then iex dies
on missing git. Reset+update the source once, pin --source winget, retry
without the pin, then fail loudly if the index is still empty.