test(vd960DBN): 二分卡死点 — 注释 json_sensor_callback enter PRINT + 删冗余打印

现场: LUP 帧后卡死 (5分钟后神秘复位 RST=0x10000000, marker丢失)。
卡死点在 lup_process_frame 内 json_sensor_callback 的 enter PRINT
(printf %d 处理), LUP Rx 打印(%s)成功但 enter(%d%d%d)卡死。
实验:
- json_sensor_callback enter PRINT #if 0 (坐实 printf 问题)
- uart_srv 187-190 重复逐字节打印 #if 0 (LUP Rx 已缓冲打印, 冗余)
验证: 不卡死→printf %d 问题实锤; 仍卡死→json_sensor_callback 后续代码

vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/tcp_json_srv.c

@@ -874,8 +874,12 @@ static int format_loop_param_json(char *buf, uint16_t buf_size, const LUP_ParamG
 static void json_sensor_callback(const uint8_t *pkg, uint16_t len)
 {
     FAULT_MARKER(MK_EVT_CB_IN);
+    /* 2026-08-13 实验: enter PRINT 是 LUP 帧后卡死嫌疑点 (printf %d 处理死循环),
+       注释验证 — 若卡死消失则坐实 printf 问题, 再深挖 _write/锁 */
+#if 0
     PRINT("JSON: sensor_cb enter socket=%d auth=%d report=%d\n",
           g_json_socket_listen, g_json_auth_state, g_report_cfg.enable);
+#endif
 
     // Check: socket active, authed, report enabled
     if (g_json_socket_listen == 0xFF) { PRINT("JSON: sensor_cb skip: no socket\n"); return; }