Add optimality note: exhaustive enumeration confirms magnitude 6 is minimum

README.md

@@ -73,6 +73,10 @@ Each input has veto power. This is unanimous consent.
 | Bias | -3 |
 | **Total** | **4 parameters** |
 
+## Optimality
+
+Exhaustive enumeration of all 1,289 weight configurations at magnitudes 0-6 confirms this circuit is **already at minimum magnitude (6)**. There is exactly one valid configuration at magnitude 6, and no valid configurations exist below it.
+
 ## Usage
 
 ```python