Resolution as 512/1024 radio (no intermediates); clarify in info that PiD picks 2k vs 2kto4k accordingly

app.py

@@ -377,7 +377,7 @@ with gr.Blocks(theme=gr.themes.Citrus(), css=CSS) as demo:
 
     with gr.Accordion("Advanced settings", open=False):
         with gr.Row():
-            resolution = gr.Slider(label="Z-Image resolution", minimum=256, maximum=1024, step=128, value=512)
+            resolution = gr.Radio(label="Z-Image resolution", choices=[512, 1024], value=512, info="512 → 2048² (PiD 2k); 1024 → 4096² (PiD 2kto4k)")
             num_inference_steps = gr.Slider(label="Z-Image steps", minimum=8, maximum=50, step=1, value=28)
         with gr.Row():
             guidance_scale = gr.Slider(label="Guidance", minimum=1.0, maximum=10.0, step=0.5, value=5.0)