chore: silence GNSS application logs by default

ql-application/threadx/interface/custom_app/inc/app_gnss_log.h

@@ -0,0 +1,18 @@
+#ifndef APP_GNSS_LOG_H
+#define APP_GNSS_LOG_H
+
+/* GNSS diagnostics are quiet by default while investigating voice replies.
+ * Define APP_GNSS_LOG_ENABLED=1 at build time to restore application logs.
+ * Keep state changes and hardware operations outside log arguments. */
+#ifndef APP_GNSS_LOG_ENABLED
+#define APP_GNSS_LOG_ENABLED 0
+#endif
+
+#if APP_GNSS_LOG_ENABLED
+#include <stdio.h>
+#define APP_GNSS_LOG(...) printf(__VA_ARGS__)
+#else
+#define APP_GNSS_LOG(...) ((void)0)
+#endif
+
+#endif