app: auto-refresh leaderboard + bootstrap logging

Step 6 (E) chunk 5 plus a diagnostic.

Auto-refresh:
- gr.Dataframe now takes `value=load_leaderboard` (callable, not
its call result) plus `every=10`. Gradio re-invokes the function
every 10 seconds and re-renders the dataframe, so pending rows
visibly flip to completed / failed and freshly-submitted rows
appear within 10s without any user action. Manual Refresh
button stays as an "I want it now" override.

Logging bootstrap:
- logging.basicConfig(level=INFO, ...) at app startup so the
`logger.info` / `logger.warning` / `logger.exception` calls
already sprinkled through leaderboard.py and submit.py reach
the Space's runtime logs. Without this they go nowhere
(Python's default no-handler behaviour), which is why every
refresh / worker pathology so far has been silent.

Combined push: the auto-refresh might not surface new rows if
the underlying load_leaderboard returns stale data on the Space
for any reason (CDN, auth, frontend re-render bug); the bootstrap
makes the next round of diagnostics actually visible instead of
guesswork.

app.py

@@ -5,6 +5,8 @@ Read path lives in :mod:`leaderboard`. Submit-tab validation lives in
 """
 from __future__ import annotations
 
+import logging
+
 import gradio as gr
 
 from leaderboard import (
@@ -14,6 +16,15 @@ from leaderboard import (
 )
 from submit import handle_submit
 
+# Surface module-level logger.info / logger.warning / logger.exception
+# calls from leaderboard.py + submit.py in the Space's runtime logs.
+# Otherwise they go nowhere and any refresh / worker pathology is
+# silent. Format keeps timestamps + module + level + message.
+logging.basicConfig(
+    level=logging.INFO,
+    format="%(asctime)s %(levelname)s [%(name)s] %(message)s",
+)
+
 
 ABOUT_MD = f"""## About
 
@@ -39,10 +50,11 @@ with gr.Blocks(title="CADGenBench Leaderboard") as app:
 
     with gr.Tab("Leaderboard"):
         df_view = gr.Dataframe(
-            value=load_leaderboard(),
+            value=load_leaderboard,
             interactive=False,
             wrap=True,
             label="Results (sorted by aggregate CAD score)",
+            every=10,
         )
         refresh_btn = gr.Button("Refresh", size="sm")
         refresh_btn.click(fn=load_leaderboard, outputs=df_view)