feat(validation): archive key result assets

Keep key validation outputs and analysis tables tracked directly,
package analysis plot PNGs into a small tar.gz backup, and add
analysis scripts plus tests so the stored results remain
reproducible without flooding git with large image trees.

pyproject.toml

@@ -16,6 +16,7 @@ dependencies = [
   "matplotlib>=3.10",
   "numpy>=1.26",
   "pandas>=2.2",
+  "seaborn>=0.13",
 ]
 
 [project.scripts]