Fix incorrect expected value in zero-length-task test (#472 review)

The relaxed-validator test asserted Min(14) but the actual weighted
completion time for lengths [0,1,3], weights [3,5,1], schedule [0,1,2]
is 3*0 + 5*1 + 1*4 = 9. Surfaced during structural review of #472.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: isPANN

src/unit_tests/models/misc/sequencing_to_minimize_weighted_completion_time.rs

@@ -147,7 +147,9 @@ fn test_sequencing_to_minimize_weighted_completion_time_zero_length_task() {
         SequencingToMinimizeWeightedCompletionTime::new(vec![0, 1, 3], vec![3, 5, 1], vec![]);
 
     assert_eq!(problem.lengths(), &[0, 1, 3]);
-    assert_eq!(problem.evaluate(&[0, 0, 0]), Min(Some(14)));
+    // Lehmer [0,0,0] decodes to schedule [0,1,2]; C = [0, 1, 4]; weighted sum
+    // = 3*0 + 5*1 + 1*4 = 9.
+    assert_eq!(problem.evaluate(&[0, 0, 0]), Min(Some(9)));
 }
 
 #[test]