chore: downgrade to Gradio 4.x for compatibility

- Lock gradio to >=4.0,<5.0 in requirements.txt
- Revert theme/css to gr.Blocks() constructor (4.x style)
- Restore type='messages' in gr.Chatbot (4.x style)
- Update README sdk_version to 4.43.0

README.md

@@ -4,7 +4,7 @@ emoji: 📖
 colorFrom: red
 colorTo: purple
 sdk: gradio
-sdk_version: 5.23.0
+sdk_version: 4.43.0
 app_file: app.py
 python_version: "3.10"
 pinned: false

app.py

@@ -1758,6 +1758,11 @@ 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(
@@ -1802,6 +1807,7 @@ def build_app() -> gr.Blocks:
                 chatbot = gr.Chatbot(
                     label="故事",
                     height=480,
+                    type="messages",
                 )
 
                 location_map_panel = gr.Markdown(
@@ -1997,9 +2003,4 @@ 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,
     )

requirements.txt

@@ -1,4 +1,4 @@
 openai>=1.0.0
-gradio>=4.0.0
+gradio>=4.0,<5.0
 python-dotenv>=1.0.0
 pydantic>=2.0.0