fix: resolve Gradio 6.x compatibility issues

- Remove deprecated 'type' parameter from gr.Chatbot (removed in Gradio 6.x)
- Move theme and css from gr.Blocks constructor to demo.launch() method

app.py

@@ -1758,11 +1758,6 @@ def build_app() -> gr.Blocks:
 
     with gr.Blocks(
         title="StoryWeaver - 交互式叙事系统",
-        theme=gr.themes.Soft(
-            primary_hue="emerald",
-            secondary_hue="blue",
-        ),
-        css=APP_UI_CSS,
     ) as app:
 
         gr.Markdown(
@@ -1807,7 +1802,6 @@ def build_app() -> gr.Blocks:
                 chatbot = gr.Chatbot(
                     label="故事",
                     height=480,
-                    type="messages",
                 )
 
                 location_map_panel = gr.Markdown(
@@ -2003,4 +1997,9 @@ if __name__ == "__main__":
         share=False,
         show_error=True,
         allowed_paths=[str(IMAGE_DIR)],
+        theme=gr.themes.Soft(
+            primary_hue="emerald",
+            secondary_hue="blue",
+        ),
+        css=APP_UI_CSS,
     )