Fix runtime error: move theme/css from launch() to Blocks() constructor

gr.Blocks.launch() does not accept theme or css kwargs — these are
constructor parameters. Moves them to gr.Blocks() where they belong.

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

app.py

@@ -1238,6 +1238,8 @@ def create_interface():
     """Build the complete Gradio interface."""
 
     with gr.Blocks(
+        theme=gr.themes.Soft(),
+        css=CUSTOM_CSS,
         title="Codette v2.0",
     ) as demo:
 
@@ -1446,4 +1448,4 @@ Created by **Jonathan Harrison** to explore recursive reasoning, multi-perspecti
 
 if __name__ == "__main__":
     demo = create_interface()
-    demo.launch(theme=gr.themes.Soft(), css=CUSTOM_CSS)
+    demo.launch()