timeline: add nip50 search timelines

Fixes: https://github.com/damus-io/notedeck/issues/456
Signed-off-by: William Casarin <jb55@jb55.com>

crates/notedeck_columns/src/ui/column/header.rs

@@ -436,6 +436,7 @@ impl<'a> NavTitle<'a> {
 
                 TimelineKind::Universe
                 | TimelineKind::Algo(_)
+                | TimelineKind::Search(_)
                 | TimelineKind::Notifications(_)
                 | TimelineKind::Generic(_)
                 | TimelineKind::List(_) => {