fix: the condition dropdown's tooltip names all four shapes without listing them

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ui.cpp

@@ -6938,8 +6938,7 @@ GtkWidget* build_trigger_panel(App& app) {
   const char* types[] = {"edge", "pulse width", "window", "dropout", nullptr};
   app.trigger_type_drop = gtk_drop_down_new_from_strings(types);
   gtk_widget_set_tooltip_text(app.trigger_type_drop,
-                              "what counts as an event: a level crossing, or a pulse whose "
+                              "what counts as an event: the dropdown lists all four shapes");
-                              "width satisfies the comparison below");
   gtk_box_append(GTK_BOX(box), labeled_box("condition", app.trigger_type_drop));
 
   const char* edges[] = {"rising", "falling", "both", nullptr};