Just to close the loop, here’s the incredibly clunky workflow I’ve come up with to address this issue:
When I want an opening single quote followed by a word that begins with N, I can type that quote and then a nonbreaking space and then the N in Blogger’s Compose mode. That gives me the correctly oriented opening quote. Then I revert to raw HTML, remove the space, and the quote remains correctly oriented when I return to Compose mode—so long as I type nothing adjacent to the quote or the word that follows.
Not great, but it works.
Again, thanks for helping me brainstorm this edge case, friends!