Remove scikit-learn from core dependencies

sklearn was listed as a core dep but governance only uses polars, jinja2,
numpy, and scipy — no sklearn calls in source. Removed to avoid pulling in
a heavyweight transitive dep unnecessarily.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: burningcost

pyproject.toml

@@ -57,7 +57,6 @@ classifiers = [
 dependencies = [
     "polars>=1.0",
     "jinja2>=3.1.0",
-    "scikit-learn>=1.3.0",
     "numpy>=2.0",
     "scipy>=1.10.0",
 ]