Disable experimental Gradio SSR mode

Gradio 6.0.1's SSR ⚡ (experimental) rendering made the Video/File output
components show a bare "Error" badge on load, with no exception in the
container logs. Gradio's own startup message points at this: "to disable
set ssr_mode=False in launch()".

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app.py

@@ -225,4 +225,4 @@ with gr.Blocks() as demo:
     demo.load(fn=preview_effect, inputs=preview_inputs, outputs=effect_preview)
 
 if __name__ == "__main__":
-    demo.queue().launch(show_error=True)
+    demo.queue().launch(show_error=True, ssr_mode=False)