feat(vscode-ide-companion): improve message handling and diff auto-opening

- Ignore messages during checkpoint saves in WebViewProvider
- Move diff auto-opening logic from useEffect to useWebViewMessages hook
- Remove unused imports and variables in EditToolCall component
- Enhance tool call handling for edit operations with diff content

packages/vscode-ide-companion/src/webview/WebViewProvider.ts

@@ -57,6 +57,20 @@ export class WebViewProvider {
     });
 
     // Setup agent callbacks
+    this.agentManager.onMessage((message) => {
+      // Ignore history replay while background /chat save is running
+      if (this.messageHandler.getIsSavingCheckpoint()) {
+        console.log(
+          '[WebViewProvider] Ignoring message during checkpoint save',
+        );
+        return;
+      }
+      this.sendMessageToWebView({
+        type: 'message',
+        data: message,
+      });
+    });
+
     this.agentManager.onStreamChunk((chunk: string) => {
       // Ignore stream chunks from background /chat save commands
       if (this.messageHandler.getIsSavingCheckpoint()) {