feat(ch934x): 添加GPIO方向控制和串口参数配置功能

- 添加Ch934xMode和GpioDirection枚举类定义
- 实现GPIO方向控制相关方法(setGpioDir/queryGpioDirFromCache)
- 添加GPIO使能控制(enableGpio)和数量/组数查询(getGpiocount/getGpiogroup)
- 实现串口参数配置(setSerialParameter)包括波特率/数据位/停止位/校验位/流控
- 添加Break信号控制(setBreak)功能
- 实现当前串口模式查询(getCurrentMode)
- 添加设备连接状态查询(isConnected)和已打开设备列表获取(getConnectedDevices)
- 更新文档说明GPIO方向控制和串口参数配置用法
- 在示例应用中添加相关功能按钮和操作逻辑

lib/ch934x_serial_method_channel.dart

@@ -215,6 +215,117 @@ class MethodChannelCh934xSerial extends Ch934xSerialPlatform {
     );
   }
 
+  @override
+  Future<bool> setBreak(bool valid) {
+    return methodChannel.invokeMethod<bool>(
+      'setBreak',
+      <String, Object>{'valid': valid},
+    ).then((v) => v ?? false);
+  }
+
+  @override
+  Future<int> getCurrentMode() {
+    return methodChannel.invokeMethod<int>('getCurrentMode')
+        .then((v) => v ?? -1);
+  }
+
+  @override
+  Future<int> getGpiocount(int deviceId) {
+    return methodChannel.invokeMethod<int>(
+      'getGPIOCount',
+      <String, Object>{'deviceId': deviceId},
+    ).then((v) => v ?? -1);
+  }
+
+  @override
+  Future<int> getGpiogroup(int deviceId) {
+    return methodChannel.invokeMethod<int>(
+      'getGPIOGroup',
+      <String, Object>{'deviceId': deviceId},
+    ).then((v) => v ?? -1);
+  }
+
+  @override
+  Future<bool> enableGpio({
+    required int chipType,
+    required int gpioGroup,
+    required int enable,
+  }) {
+    return methodChannel.invokeMethod<bool>(
+      'enableGPIO',
+      <String, Object>{
+        'chipType': chipType,
+        'gpioGroup': gpioGroup,
+        'enable': enable,
+      },
+    ).then((v) => v ?? false);
+  }
+
+  @override
+  Future<bool> setGpioDir({
+    required int gpioGroup,
+    required int gpioNumber,
+    required int dir,
+  }) {
+    return methodChannel.invokeMethod<bool>(
+      'setGPIODir',
+      <String, Object>{
+        'gpioGroup': gpioGroup,
+        'gpioNumber': gpioNumber,
+        'dir': dir,
+      },
+    ).then((v) => v ?? false);
+  }
+
+  @override
+  Future<int> queryGpioDirFromCache({
+    required int gpioGroup,
+    required int gpioNumber,
+  }) {
+    return methodChannel.invokeMethod<int>(
+      'queryGPIODirFromCache',
+      <String, Object>{
+        'gpioGroup': gpioGroup,
+        'gpioNumber': gpioNumber,
+      },
+    ).then((v) => v ?? -1);
+  }
+
+  @override
+  Future<bool> isConnected(int deviceId) {
+    return methodChannel.invokeMethod<bool>(
+      'isConnected',
+      <String, Object>{'deviceId': deviceId},
+    ).then((v) => v ?? false);
+  }
+
+  @override
+  Future<List<int>> getConnectedDevices() async {
+    final raw = await methodChannel.invokeMethod<List<dynamic>>('getConnectedDevices');
+    if (raw == null) return const <int>[];
+    return raw.whereType<int>().toList(growable: false);
+  }
+
+  @override
+  Future<bool> setSerialParameter({
+    required int baud,
+    int dataBit = 8,
+    int stopBit = 1,
+    int parityBit = 0,
+    bool flow = false,
+  }) {
+    return methodChannel.invokeMethod<bool>(
+      'setSerialParameter',
+      <String, Object>{
+        'baud': baud,
+        'dataBit': dataBit,
+        'stopBit': stopBit,
+        'parityBit': parityBit,
+        'flow': flow,
+      },
+    ).then((v) => v ?? false);
+  }
+
   /// 释放内部资源,通常仅在测试或热重载场景下使用。
   @visibleForTesting
   void dispose() {