Write Brief: Don't spell check code blocks

Currently we spell check code blocks, which leads to lots of red underlines in those blocks. We might want to ignore them entirely, as well as for other Write Brief features (we probably don't need to check for long sentences or unconfident words either). I would say that the exception maybe for comments, which could be spell checked, but that's likely too much work to deal with.

Start at the Write Brief entry point and trace how spell checking and the other Write Brief checks process code blocks. The work is done when code blocks no longer produce spell-check, long-sentence, or unconfident-word findings, while the treatment of comments is explicitly resolved.

Written by the indexing model from the issue text.