adding a button for fixing all errors (#1785)

closes #1688 



<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Add a “Fix All Errors” button to the chat that collects all error
messages and sends a single request to resolve them. This helps users
fix multiple errors in one step.

- New Features
- Parse dyad-output type=error messages and track count/last index in
DyadMarkdownParser.
- Show FixAllErrorsButton after the last error when there are 2+ errors,
not streaming, and chatId is present.
- Button streams a prompt listing all errors, shows a loading state, and
displays the error count.

<sup>Written for commit b9762955d3b9cecd3b00c9efb478ce599f60e32d.
Summary will update automatically on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

e2e-tests/fixtures/create-multiple-errors.md

@@ -0,0 +1,55 @@
+I will intentionally add multiple errors to test the Fix All Errors button
+
+<dyad-write path="src/pages/Index.tsx" description="intentionally add first error">
+// Update this page (the content is just a fallback if you fail to update the page)
+
+import { MadeWithDyad } from "@/components/made-with-dyad";
+
+const Index = () => {
+throw new Error("First error in Index");
+return (
+
+<div className="min-h-screen flex items-center justify-center bg-gray-100">
+<div className="text-center">
+<h1 className="text-4xl font-bold mb-4">Welcome to Your Blank App</h1>
+<p className="text-xl text-gray-600">
+Start building your amazing project here!
+</p>
+</div>
+<MadeWithDyad />
+</div>
+);
+};
+
+export default Index;
+</dyad-write>
+
+<dyad-output type="error" message="First error in Index">
+Error: First error in Index
+    at Index (http://localhost:5173/src/pages/Index.tsx:6:7)
+</dyad-output>
+
+<dyad-write path="src/components/ErrorComponent.tsx" description="intentionally add second error">
+const ErrorComponent = () => {
+  throw new Error("Second error in ErrorComponent");
+  return <div>This will never render</div>;
+};
+
+export default ErrorComponent;
+</dyad-write>
+
+<dyad-output type="error" message="Second error in ErrorComponent">
+Error: Second error in ErrorComponent
+    at ErrorComponent (http://localhost:5173/src/components/ErrorComponent.tsx:2:9)
+</dyad-output>
+
+<dyad-write path="src/utils/helper.ts" description="intentionally add third error">
+export const brokenHelper = () => {
+  throw new Error("Third error in helper");
+};
+</dyad-write>
+
+<dyad-output type="error" message="Third error in helper">
+Error: Third error in helper
+    at brokenHelper (http://localhost:5173/src/utils/helper.ts:2:9)
+</dyad-output>