Add missing header logo PNG and tighten title spacing

The deployed app.py already references assets/logo.png (via
_logo_data_uri), but the binary was never committed, so the Space
build crashed with FileNotFoundError. Commit the transparent,
content-cropped wordmark and snug up the title block (smaller logo
height + collapsed flex gap) so it sits directly above the tabs.

Co-authored-by: Cursor <cursoragent@cursor.com>

app.py

@@ -994,8 +994,13 @@ def _logo_data_uri() -> str:
 _APP_CSS = (
     "footer{display:none !important;}"
     ".gradio-container{padding-top:4px !important; padding-bottom:0 !important;}"
-    "#cgb-title{margin-bottom:0 !important;}"
-    "#cgb-title .cgb-logo{height:64px;width:auto;display:block;margin:2px 0;}"
+    # Collapse the title block's own box and the flex gap Gradio puts
+    # between it and the tab bar so the wordmark sits right above the
+    # leaderboard instead of floating with a gap. The negative bottom
+    # margin pulls the tab nav up snug against the logo.
+    "#cgb-title{margin:0 !important;padding:0 !important;min-width:0 !important;}"
+    "#cgb-title .cgb-logo{height:46px;width:auto;display:block;margin:0;}"
+    ".gradio-container .tabs{margin-top:-6px !important;}"
     ".dark #cgb-title .cgb-logo{filter:invert(1);}"
     "@media (prefers-color-scheme: dark){"
     "#cgb-title .cgb-logo{filter:invert(1);}}"