fix(api): preserve template preset endpoint

Keep the public preset-selection API name stable after replacing its wrapper function with direct dictionary lookup.

app.py

@@ -315,6 +315,7 @@ with gr.Blocks(title="NuMarkApp") as demo:
         structured_json_templates.__getitem__,
         inputs=template_preset,
         outputs=template,
+        api_name="select_structured_json_template",
     )
 
     generate_template_button.click(