ui: reword the docs that still spoke of the list drag; keep disabled signals' badge order; stamp the signal generation before the snapshot

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

src/ui_signals.cpp

@@ -569,6 +569,9 @@ void rebuild_signal_panels(App& app) {
   // GTK calls (a use-after-free of the name strings otherwise).
   std::vector<SignalInfo> signals;
   bool have_signals = false;
+  // The generation this build answers to is read *before* the snapshot: a CONFIG landing between the two
+  // would otherwise be stamped as seen without having been, and the tick would never rebuild for it.
+  const unsigned generation = app.model->generation();
   {
     std::lock_guard<std::mutex> lock(app.model->mutex());
     signals = app.model->signals();
@@ -585,7 +588,7 @@ void rebuild_signal_panels(App& app) {
   }
   signal_pages_sync(app);
   sync_signal_badges(app);
-  app.signal_generation = app.model->generation();
+  app.signal_generation = generation;
 }
 
 GtkWidget* build_signal_panel(App& app) {