Make write of types.json atomic

[jayvdb]

This is what Claude Sonnet 4.5 believes is the problem with #162

[jayvdb]

Possibly this error is now the same problem appearing in a new ways
https://github.com/Electron100/butane/actions/runs/18809595881/job/53668741071?pr=387
https://github.com/Electron100/butane/actions/runs/18810077107/job/53669807906?pr=387

[Electron100]

The thing that bothers me on this is that there already is a synchronization mechanism here, using file locks. It does seem that something is somehow going awry with it, but I'd love to have a theory of what it is before bandaiding in additional mechanisms. Especially since if something is wrong with the synchronization, I'm not sure types.json is the only one with a problem.

[jayvdb]

Ya I am not convinced this is a fix, and the CI runs demonstrate it only changed the errors. I'd prefer to keep the same errors until we really find the cause.