Revert "gitignore all files in /build (for prod rebase)"

This reverts commit d8c5da325df46e63c9d7a3aeaced8d9b6dd47f4d.
Revert "gitignore build css (for rebasing to production)"

This reverts commit 663019d37bb8c45892b3fd4df484fd743e68bf02.
gitignore build css (for prod rebase)

Trying this again using `/**`