fix: align slice/set equality and harden queue API

set_test.go

@@ -17,3 +17,15 @@ func TestSet(t *testing.T) {
 		t.Error("s1 and s2 not equal")
 	}
 }
+
+func TestSet_EqualIgnoresCapacity(t *testing.T) {
+	s1 := make(Set[int], 2, 2)
+	s2 := make(Set[int], 2, 4)
+
+	s1[0], s1[1] = 1, 2
+	s2[0], s2[1] = 1, 2
+
+	if !s1.Equal(s2) {
+		t.Error("s1 and s2 not equal")
+	}
+}