Add optimality note: exhaustive enumeration confirms magnitude 3 is minimum

README.md

@@ -48,6 +48,10 @@ AND and OR are the same circuit with different thresholds. This is the essence o
 | Bias | -1 |
 | Total | 3 parameters |
 
+## Optimality
+
+Exhaustive enumeration of all 25 weight configurations at magnitudes 0-3 confirms this circuit is **already at minimum magnitude (3)**. There is exactly one valid configuration at magnitude 3, and no valid configurations exist below it.
+
 ## Properties
 
 - Linearly separable