fix: Add type assertion for MDX components to resolve React 19 compatibility

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

apps/docs/mdx-components.tsx

@@ -5,5 +5,5 @@ export function useMDXComponents(components: MDXComponents): MDXComponents {
   return {
     ...defaultComponents,
     ...components,
-  };
+  } as MDXComponents;
 }