feat: add outlier score formula and save decision

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/lib/score.js

@@ -0,0 +1,9 @@
+export function computeScore(views, subscribers) {
+  if (subscribers === null || subscribers === undefined) return null;
+  return Math.round((views / Math.max(subscribers, 1)) * 100) / 100;
+}
+
+export function shouldSave({ views, score, vidiqScore }, { threshold, minViews }) {
+  if (vidiqScore !== null && vidiqScore !== undefined) return true;
+  return score !== null && score !== undefined && views >= minViews && score >= threshold;
+}