Give each route its own title and canonical, and add robots.txt plus a sitemap.

The root layout was stamping the homepage title and production root onto every page. Routes now supply a page segment through one em-dash template, canonicals follow the request path, and non-production hosts disallow crawlers.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/(dev)/layout.tsx

@@ -1,8 +1,14 @@
 import type { ReactNode } from "react";
+import type { Metadata } from "next";
 import { notFound } from "next/navigation";
 import { MessagesProvider } from "../contexts/MessagesContext";
 import { AuthModalProvider } from "../contexts/AuthModalContext";
 import messages from "../../messages/en/index";
+import { NO_INDEX_ROBOTS } from "../../lib/siteMetadata";
+
+export const metadata: Metadata = {
+  robots: NO_INDEX_ROBOTS,
+};
 
 // Development-only previews (e.g. `/components-preview`) — no public chrome.
 export default function DevLayout({ children }: { children: ReactNode }) {