Add initial setup for Fumadocs documentation migration

- Created new directory structure for documentation under `/docs2`.
- Added `.gitignore` to exclude build artifacts and dependencies.
- Introduced `package.json`, `next.config.mjs`, and `postcss.config.mjs` for project configuration.
- Implemented MDX components in `mdx-components.tsx` for rendering documentation.
- Migrated existing documentation content and created new files for auto-updater and other features.
- Established compatibility layer for Mintlify components in `mintlify-compat.tsx`.
- Set up OpenAPI documentation in `openapi.json`.
- Updated README and migration guide to reflect new structure and usage instructions.
- Ensured all components and pages are ready for development and deployment with Fumadocs.

docs2/app/(home)/layout.tsx

@@ -0,0 +1,6 @@
+import { HomeLayout } from 'fumadocs-ui/layouts/home';
+import { baseOptions } from '@/lib/layout.shared';
+
+export default function Layout({ children }: LayoutProps<'/'>) {
+  return <HomeLayout {...baseOptions()}>{children}</HomeLayout>;
+}

docs2/app/(home)/page.tsx

@@ -0,0 +1,16 @@
+import Link from 'next/link';
+
+export default function HomePage() {
+  return (
+    <div className="flex flex-col justify-center text-center flex-1">
+      <h1 className="text-2xl font-bold mb-4">Hello World</h1>
+      <p>
+        You can open{' '}
+        <Link href="/docs" className="font-medium underline">
+          /docs
+        </Link>{' '}
+        and see the documentation.
+      </p>
+    </div>
+  );
+}