feat(vscode-ide-companion): add cancel streaming functionality

- Add handleCancel callback to App component
- Implement cancelStreaming message posting to VS Code
- Add onCancel prop to InputForm component
- Replace send button with stop button during streaming

packages/vscode-ide-companion/src/webview/utils/tempFileManager.ts

@@ -0,0 +1,33 @@
+/**
+ * @license
+ * Copyright 2025 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Temporary file manager for creating and opening temporary files in webview
+ */
+
+/**
+ * Creates a temporary file with the given content and opens it in VS Code
+ * @param content The content to write to the temporary file
+ * @param fileName Optional file name (without extension)
+ * @param fileExtension Optional file extension (defaults to .txt)
+ */
+export async function createAndOpenTempFile(
+  postMessage: (message: {
+    type: string;
+    data: Record<string, unknown>;
+  }) => void,
+  content: string,
+  fileName: string = 'temp',
+  fileExtension: string = '.txt',
+): Promise<void> {
+  // Send message to VS Code extension to create and open temp file
+  postMessage({
+    type: 'createAndOpenTempFile',
+    data: {
+      content,
+      fileName,
+      fileExtension,
+    },
+  });
+}