docs: explain best-effort stream reconfigure in validate_scores

Address github-code-quality review: the except (AttributeError, ValueError)
guard around stream reconfigure was an undocumented empty swallow. Add a
comment noting it is best-effort (wrapped streams such as pytest's capture
object do not support reconfigure). No functional change.

Author: Oseltamivir

utils/evals/validate_scores.py

@@ -200,6 +200,8 @@ def main() -> int:
         try:
             _stream.reconfigure(line_buffering=True)
         except (AttributeError, ValueError):
+            # Best-effort only: some wrapped streams (e.g. pytest's capture
+            # object) don't support reconfigure; leave their buffering as-is.
             pass
 
     parser = argparse.ArgumentParser(description="Validate eval scores")