fix(rs485): 频率改用 loop1_CAPVD，绕过 flag_change 冻结

g_loop_acs_info.loop_capvd 被 flag_change 门控:
  INIT_VD() / 车辆进出事件 → flag_change=1 → loop_capvd 冻结
  flag_change 仅在 usart_packet_processing_acs_loop 清零
  BLE 断开时 flag_change 永远不清零 → loop_capvd 永远不更新

改用 loop1_CAPVD (vd1_task 每次实时更新，不受 flag_change 影响)

BLE/DLD154Pro_Peripheral_28K/APP/rs485_700bs.c

@@ -90,10 +90,10 @@ static void rs485_send(const uint8_t *data, uint8_t len)
 /* 直接从原始测量值计算线圈频率 (Hz)，不依赖 BLE 报告通道 */
 static uint32_t rs485_get_freq(void)
 {
-    uint32_t capvd = g_loop_acs_info.loop_capvd;  // TMR0 捕获累加值
-    if (capvd == 0 || loop1_LPCNT == 0) return 0;
-    /* freq = FREQ_SYS / (capvd / LPCNT) + 360 (补偿值) */
-    return (uint32_t)((uint64_t)FREQ_SYS * loop1_LPCNT / capvd) + 360;
+    extern uint32_t loop1_CAPVD;  // vd1_task() 实时更新的 IIR 滤波值
+    if (loop1_CAPVD == 0 || loop1_LPCNT == 0) return 0;
+    /* freq = FREQ_SYS / (CAPVD / LPCNT) + 360 (补偿值) */
+    return (uint32_t)((uint64_t)FREQ_SYS * loop1_LPCNT / loop1_CAPVD) + 360;
 }
 
 /* 0xFA — 查询有车状态 + 线圈好坏 */