nmbug-status: Use <code> and <p> markup where appropriate
* Wrap free text in <p> tags.
* Convert <blockquote> to <p><code> for query strings.
* Wrap message-id-term (id:"...") in <code>.
The <code> tags get nicer default markup (smaller monospace font) for
notmuch query terms [1]. The <p> tags don't have much effect without
attached CSS, but bare text (phrasing content [2]) in <body> (which
expects flow content [3,4]) feels wrong.