Label text stages in the chain list with their words

Effect::label(values) names a stage in a list, defaulting to the title;
the text effect answers "Text (words)", and the chain rows are renamed
in place as params change.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/gui/window.hpp

@@ -95,6 +95,7 @@ private:
     // The check on a chain row: the stage stays where it is, and is skipped.
     void setStageEnabled(int index, bool enabled);
     void rebuildChainRows();
+    std::string stageLabel(std::size_t index) const;
     void selectStage(int index);
     void onStageSelected();
     Gtk::Widget& buildMainMenu();     // the header menu: new, open, save project
@@ -145,6 +146,8 @@ private:
     StyleSet styles_;
     int selectedStage_ = 0;
     bool suspendStageSelect_ = false;  // guards the rebuild of the chain rows
+    // The name label of each chain row, renamed in place as params change.
+    std::vector<Gtk::Label*> stageLabels_;
     Image result_;
     std::uint64_t seed_ = 0;
     std::string projectPath_;  // empty until the project has been saved once