chore(pygal): set quality score 72 for waterfall-basic

Author: github-actions[bot]

plots/waterfall-basic/metadata/pygal.yaml

@@ -15,7 +15,7 @@ current:
   generated_by: claude-opus-4-5-20251101
   workflow_run: 20207313656
   issue: 777
-  quality_score: 80
+  quality_score: 72
   # Version info (filled by workflow)
   python_version: "3.13.11"
   library_version: "unknown"