Use next-themes in theme provider for React frontends, and fix neon setup (#407)

Co-authored-by: Aman Varshney <amanvarshney.work@gmail.com>

apps/cli/templates/frontend/react/react-router/src/routes/_index.tsx.hbs

@@ -29,7 +29,7 @@ const TITLE_TEXT = `
  `;
 
 export function meta({}: Route.MetaArgs) {
-  return [{ title: "My App" }, { name: "description", content: "My App" }];
+  return [{ title: "{{projectName}}" }, { name: "description", content: "{{projectName}} is a web application" }];
 }
 
 export default function Home() {