fix Windows build.dart to avoid native_assets fork; add implementations for ThermionFlutterWindows

thermion_flutter/thermion_flutter_platform_interface/lib/thermion_flutter_platform_interface.dart

@@ -4,6 +4,7 @@ import 'package:thermion_dart/thermion_dart.dart' as t;
 import 'package:plugin_platform_interface/plugin_platform_interface.dart';
 import 'package:thermion_dart/thermion_dart.dart';
 import 'thermion_flutter_texture.dart';
+import 'thermion_flutter_window.dart';
 
 class ThermionFlutterOptions {
   final String? uberarchivePath;
@@ -41,7 +42,13 @@ abstract class ThermionFlutterPlatform extends PlatformInterface {
       t.View view, int width, int height);
 
   ///
+  /// Create a rendering window.
   ///
+  /// This is internal; unless you are [thermion_*] package developer, don't
+  /// call this yourself. May not be supported on all platforms.
   ///
-  Future resizeWindow(int width, int height, int offsetTop, int offsetRight);
+  Future<ThermionFlutterWindow> createWindow(
+      int width, int height, int offsetLeft, int offsetTop);
+
+  
 }

thermion_flutter/thermion_flutter_platform_interface/lib/thermion_flutter_window.dart

@@ -0,0 +1,16 @@
+abstract class ThermionFlutterWindow {
+
+  int get width;
+  int get height;
+
+  int get handle;
+
+  ///
+  /// Destroy a texture and clean up the texture cache (if applicable).
+  ///
+  Future destroy();
+
+  Future resize(int width, int height, int left, int top);
+
+  Future markFrameAvailable();
+}