feat: Windows增加分辨率适应，切换分辨率按钮修改

webrtc_controller_flutter/windows/runner/flutter_window.h

@@ -3,6 +3,8 @@
 
 #include <flutter/dart_project.h>
 #include <flutter/flutter_view_controller.h>
+#include <flutter/method_channel.h>
+#include <flutter/standard_method_codec.h>
 
 #include <memory>
 
@@ -23,11 +25,20 @@ class FlutterWindow : public Win32Window {
                          LPARAM const lparam) noexcept override;
 
  private:
+  // 按给定的视频宽高比（宽/高）调整窗口：保持窗口宽度不变，
+  // 高度按比例计算；若高度超出屏幕工作区，则以屏幕高度为准
+  // 反推出合适的窗口宽高。
+  void ResizeToVideoAspect(double aspect);
+
   // The project to run.
   flutter::DartProject project_;
 
   // The Flutter instance hosted by this window.
   std::unique_ptr<flutter::FlutterViewController> flutter_controller_;
+
+  // 与 Dart 层通信的窗口控制通道。
+  std::unique_ptr<flutter::MethodChannel<flutter::EncodableValue>>
+      window_channel_;
 };
 
 #endif  // RUNNER_FLUTTER_WINDOW_H_