What is the proper term for lead time from commit to deployment?
From code repository to any environment, as a running software would be "Time to Deploy" ( which is different from deployment time, btw ).

From code repository all the way to production environment, the best aproximation is time to market (TTM), taking aside that time to market does involve the conceptual design of a product.

But as you said you are tagging an pipeline, I should advise:

Use the tags that makes sense: to you, your team and to your product. 

A common pipeline could be : BUILD > TEST > DEPLOY 

But we could tag the same pipeline, making more steps visible, ie :
SOURCE CHECKOUT > CODE CHECK > UNITARY TESTS > BUILD > INTEGRATED TESTS > DEPLOY > ACCEPTANCE TESTS

As a rule, if you have trouble on one step and must check the output to understand whats going on, this step could be divided in one or more tags.

If makes sense to you, you could even tag something like SOURCE CHECKOUT IDLE TIME ( the time took for the build machine to connect to the repository server, before downloading the source )

Hope this could be useful, happy tagging!