fix (vscode): focus chat input after opening the chat view

Opens the chat view before focusing the input
Routes a new webview command to focus the composer
Refocuses the input after adding a VS Code selection attachment

packages/vscode/src/ChatViewProvider.ts

@@ -200,6 +200,18 @@ export class ChatViewProvider implements vscode.WebviewViewProvider {
     }
   }
 
+  public focusChatInput(): void {
+    if (!this._view) {
+      return;
+    }
+
+    this._view.show(true);
+    void this._view.webview.postMessage({
+      type: 'command',
+      command: 'focusChatInput',
+    });
+  }
+
   public addContextSelection(selection: { filePath: string; filename: string; text: string }) {
     if (!this._view) {
       return;