Update Hearing Type Definition

[Mephistic]

It seems that some Hearings are missing Hearing properties - it seems that Name, and HearingHost.GeneralCourtNumber/CommitteeCode are not guaranteed. This PR updates the type definitions to make these fields nullable.

I'm not sure yet why these fields would be missing, but this should unstick a bug we're seeing with the scrapers.

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Project	Deployment	Review	Updated (UTC)
maple-dev	Ready	Preview, Comment	Dec 16, 2025 9:31pm

[Mephistic]

This took a little longer than expected because I also updated runtypes from 6.5.1 to 6.6.0 - this is a minor change that should just make the error messages around failed check()s more useful.

Also found the issue with the check-types command - our copy-handlebars script copies over all files from functions/src/email... including the raw .ts files pre-compilation, which can cause check-types to fail locally (which made the issue here more annoying to reproduce). I don't fix that in this PR, but I have another one coming that should smooth this process out to only copy over the actual handlebars templates.