Fix: Re-add login button to Gradio app

The login button was inadvertently removed during previous linting fixes,
leading to authentication issues. This commit re-adds the `gr.LoginButton`
component to the Gradio interface and suppresses the F841 linting warning
as the variable is used for UI rendering.

app.py

@@ -185,6 +185,9 @@ def build_gradio_app():
 
 
 
+        with gr.Row():
+            login_button = gr.LoginButton(min_width=250)  # noqa: F841
+
         gr.Markdown("### 1. Select a Model from the Hugging Face Hub")
         model_input = HuggingfaceHubSearch(
             label="Search for a Model",