Removing keywords: check token-kind ranges used as category tests

When deleting the last keywords from a token enum (here two reserved macro keywords), grep for range checks like kind >= KwFirst && kind <= KwLast before removing the enumerator: a language server or highlighter often classifies keywords by an enum range rather than a list, and the end marker silently names the removed kind. Move the end of the range to the new last keyword. Also check multi-character operators that contain a removed single-character token (here <$> after dropping $): they keep lexing only if operators are matched longest-first before single-character punctuation. When the working tree also holds unrelated in-progress code that doesn't build, git stash push -- <paths> stashes just those paths so the change can be tested alone.