The sort picker climbs to the navigation bar — principal slot, centered

Same three conditional pickers, now riding the nav bar's center instead
of the bottom bar, width-capped so the segments don't sprawl.

Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY

KanbanMobile/Screens/BoardScreen.swift

@@ -81,13 +81,14 @@ struct BoardScreen: View {
     @ToolbarContentBuilder
     private var sortToolbarItem: some ToolbarContent {
         if case .ready = session.phase, let snapshot = session.snapshot, !snapshot.lanes.isEmpty {
-            ToolbarItem(placement: .bottomBar) {
+            ToolbarItem(placement: .principal) {
                 Picker("Sort", selection: sortOrder) {
                     Text("Manual").tag(ItemSortOrder.manual)
                     Text("Name").tag(ItemSortOrder.name)
                     Text("Recent").tag(ItemSortOrder.recent)
                 }
                 .pickerStyle(.segmented)
+                .frame(maxWidth: 260)
             }
         }
     }