Members walk: leave descending and cursor to the Selection default

With projection gone the walk spreads Selection::default(); an explicit
descending: false was a mutant no test could tell from the default.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

crates/huginn-mind/src/query.rs

@@ -543,9 +543,7 @@ impl<S: MindStore> Mind<S> {
             fields,
             cites,
             cited,
-            descending: false,
             limit: Some(LIMIT_MAX),
-            cursor: None,
             ..Selection::default()
         };
         let mut ids = Vec::new();