fix(web): fix getting-started metadata export, use TURBOPACK=0 env for build

- generateMetadata instead of metadata (getMetadata returns a function)
- Use TURBOPACK=0 env prefix instead of --no-turbopack flag (not recognized in Docker)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/app/[locale]/(marketing)/getting-started/page.tsx

@@ -2,11 +2,11 @@ import Link from "next/link";
 
 import { getMetadata } from "~/lib/metadata";
 
-export const metadata = getMetadata({
+export const generateMetadata = getMetadata({
   title: "Getting Started",
   description:
     "Install claudemesh, join a mesh, and launch your first peer session in under two minutes.",
-})();
+});
 
 const STEP = ({
   n,