[AUTOMATED] Migration to Gradio 6.0

This PR migrates the Space to Gradio 6.0.

### Changes
- `README.md`: Updated `sdk_version` to `6.0.0`
- `app.py`: Automated refactoring using `moonshotai/Kimi-K2-Thinking` based on the migration guide.

README.md

@@ -4,7 +4,7 @@ emoji: 💻
 colorFrom: purple
 colorTo: gray
 sdk: gradio
-sdk_version: 5.44.1
+sdk_version: 6.0.0
 app_file: app.py
 pinned: false
 ---

app.py

@@ -251,7 +251,7 @@ css = '''
 #or_item{text-align: center; padding-top: 1em; padding-bottom: 1em; font-size: 1.1em;margin-left: .5em;margin-right: .5em;width: calc(100% - 1em)}
 #fivesec{margin-top: 5em;margin-left: .5em;margin-right: .5em;width: calc(100% - 1em)}
 '''
-with gr.Blocks(theme=gr.themes.Citrus(), css=css) as app:
+with gr.Blocks() as app:
     gr.Markdown("# Wan 2.2 First/Last Frame Video Fast")
     gr.Markdown("Based on the [Wan 2.2 First/Last Frame workflow](https://www.reddit.com/r/StableDiffusion/comments/1me4306/psa_wan_22_does_first_frame_last_frame_out_of_the/), applied to 🧨 Diffusers + [lightx2v/Wan2.2-Lightning](https://huggingface.co/lightx2v/Wan2.2-Lightning) 8-step LoRA")
 
@@ -332,4 +332,4 @@ with gr.Blocks(theme=gr.themes.Citrus(), css=css) as app:
     )
 
 if __name__ == "__main__":
-    app.launch(share=True)
+    app.launch(share=True, theme=gr.themes.Citrus(), css=css)