Add image previews to example selection buttons in Gradio app

Updates the example selection UI to display PNG thumbnails for each example model instead of a generic list. Uses a gr.Dataset with image components to render the previews and handles selection via a click event to load the corresponding 3D model.

app.py

@@ -250,11 +250,15 @@ def create_gradio_app(particulate_app):
     # Get example files from examples folder
     examples_dir = "examples"
     example_files = []
+    example_images = []
     if os.path.exists(examples_dir):
-        for file in os.listdir(examples_dir):
+        for file in sorted(os.listdir(examples_dir)):
             if file.lower().endswith(('.glb', '.obj')):
-                example_files.append(os.path.join(examples_dir, file))
-        example_files.sort()  # Sort for consistent ordering
+                base_name = os.path.splitext(file)[0]
+                png_path = os.path.join(examples_dir, base_name + ".png")
+                if os.path.exists(png_path):
+                    example_files.append(os.path.join(examples_dir, file))
+                    example_images.append(png_path)
     
     with gr.Blocks(title="Particulate Demo") as demo:
         gr.HTML(
@@ -304,11 +308,21 @@ def create_gradio_app(particulate_app):
                     label="Upload 3D Model", 
                     interactive=True
                 )
-                if example_files:
-                    gr.Examples(
-                        examples=[[file] for file in example_files],
-                        inputs=[input_mesh],
-                        label="Example Models"
+                if example_files and example_images:
+                    example_dataset = gr.Dataset(
+                        label="Example Models",
+                        components=[gr.Image(visible=False)],
+                        samples=[[img] for img in example_images],
+                        type="index"
+                    )
+
+                    def load_example(index):
+                        return example_files[index]
+
+                    example_dataset.click(
+                        fn=load_example,
+                        inputs=[example_dataset],
+                        outputs=[input_mesh]
                     )
                 mesh_plot = gr.Plot(label="Mesh Preview")