feat: Add new system for multi-selections.

crates/pikl-core/tests/dsl_tests.rs

@@ -286,6 +286,48 @@ pikl_tests! {
         }
     }
 
+    menu mod multi_select_basic {
+        items: ["alpha", "bravo", "charlie", "delta"];
+        multi: true;
+
+        test toggle_one_then_confirm {
+            actions: [toggle-select, confirm]
+            selected_items: ["alpha"]
+        }
+
+        test toggle_two_then_confirm {
+            actions: [toggle-select, move-down, move-down, toggle-select, confirm]
+            selected_items: ["alpha", "charlie"]
+        }
+
+        test no_selection_falls_back_to_cursor {
+            actions: [move-down, confirm]
+            selected: "bravo"
+        }
+
+        test select_all_then_confirm {
+            actions: [select-all, confirm]
+            selected_items: ["alpha", "bravo", "charlie", "delta"]
+        }
+
+        test clear_selections_resets {
+            actions: [toggle-select, move-down, toggle-select, clear-selections, confirm]
+            // Falls back to cursor item (bravo, since we moved down once)
+            selected: "bravo"
+        }
+
+        test undo_restores_previous {
+            actions: [toggle-select, move-down, toggle-select, undo-selection, confirm]
+            // Undo reverts the second toggle, only alpha remains
+            selected_items: ["alpha"]
+        }
+
+        test redo_after_undo {
+            actions: [toggle-select, move-down, toggle-select, undo-selection, redo-selection, confirm]
+            selected_items: ["alpha", "bravo"]
+        }
+    }
+
     nav mod half_page_small_height {
         viewport: { height: 2, count: 10 };