Explore options for avoiding redeployments of unchanged apps

[taesungh]

Follow-up to #206:

In addition to preview deployments, it would be nice if we could avoid redeploying the Sanity project in production if nothing has changed there since the last deployment (and vice versa for the site although less often there).

Vercel has a mechanism for skipping unaffected projects in monorepos, but that requires connecting the repository which we cannot do on the Hobby team.

This feature is only available for projects connected to GitHub repositories.

We might be able to manually replicate that by setting up ignoring the build step based on turbo-ignore. However, skipping the build still counts as a deployment.

Canceled builds initiated using the ignore build step do count towards your deployment and concurrent build limits

Therefore, we would need to somehow replicate the feature from the Actions workflow.