feat(gui): Add _render_thinking_trace helper and integrate into Discussion Hub

tests/test_thinking_gui.py

@@ -1,6 +1,14 @@
 import pytest
 
 
+def test_render_thinking_trace_helper_exists():
+    from src.gui_2 import App
+
+    assert hasattr(App, "_render_thinking_trace"), (
+        "_render_thinking_trace helper should exist in App class"
+    )
+
+
 def test_discussion_entry_with_thinking_segments():
     entry = {
         "role": "AI",
@@ -38,6 +46,7 @@ def test_thinking_segment_model_compatibility():
 
 
 if __name__ == "__main__":
+    test_render_thinking_trace_helper_exists()
     test_discussion_entry_with_thinking_segments()
     test_discussion_entry_without_thinking()
     test_thinking_segment_model_compatibility()