test: Add LogAuditEvent tests

Cover success and failure logging branches (66.7% to 100%)

internal/api/security_test.go

@@ -1036,3 +1036,36 @@ func TestSecurityHeadersWithConfig_NextHandlerCalled(t *testing.T) {
 		t.Error("next handler was not called")
 	}
 }
+
+func TestLogAuditEvent_Success(t *testing.T) {
+	// Should not panic and should log at Info level
+	LogAuditEvent(
+		"test_event",
+		"testuser",
+		"192.168.1.100",
+		"/api/test",
+		true,
+		"test details",
+	)
+	// If we got here without panic, the test passes
+}
+
+func TestLogAuditEvent_Failure(t *testing.T) {
+	// Should not panic and should log at Warn level
+	LogAuditEvent(
+		"failed_login",
+		"attacker",
+		"203.0.113.42",
+		"/api/login",
+		false,
+		"invalid credentials",
+	)
+	// If we got here without panic, the test passes
+}
+
+func TestLogAuditEvent_EmptyFields(t *testing.T) {
+	// Should handle empty strings gracefully
+	LogAuditEvent("", "", "", "", true, "")
+	LogAuditEvent("", "", "", "", false, "")
+	// If we got here without panic, the test passes
+}