test(reconcile): a number or word that merely starts with 1 or 2 is not an answer

Mutation-testing the adjudicator showed dropping the word boundary went unnoticed:
'ANSWER: 12' would be read as 1.

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

internal/reconcile/adjudicate_test.go

@@ -79,6 +79,8 @@ func TestLLMAdjudicator_MapsTheAnswerBackToBaseOrAltWhicheverOrderWasShown(t *te
 		{"no answer line is unsure, not a guess", false, "I think the first one.", reconcile.VerdictUnsure},
 		{"an empty reply is unsure", false, "", reconcile.VerdictUnsure},
 		{"an out of range number is unsure", false, "ANSWER: 3", reconcile.VerdictUnsure},
+		{"a number that merely starts with 1 is not 1", false, "ANSWER: 12", reconcile.VerdictUnsure},
+		{"a word that merely starts with 2 is not 2", false, "ANSWER: 2nd option", reconcile.VerdictUnsure},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {