fix: 添加 format_sensor_json 前置声明，修复 implicit declaration 编译错误

vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/tcp_json_srv.c

@@ -745,6 +745,11 @@ static void json_process_frame(uint8_t socket, const char *frame) {
 /*===========================================================================
  * json_sensor_callback — 注册到 lup_process_frame，0xC0 帧到达时直接推送
  *===========================================================================*/
+
+/* Forward declarations */
+static int format_sensor_json(char *buf, uint16_t buf_size, const LUP_SensorReport *sr);
+static int format_loop_param_json(char *buf, uint16_t buf_size, const LUP_ParamGet *pg);
+
 static void json_sensor_callback(const uint8_t *pkg, uint16_t len)
 {
     // Check: socket active, authed, report enabled