Wire up generateMetadata so every page actually gets dynamic SEO tags

You are adding or fixing generateMetadata for a specific route. If the page's title or description depend on real data — a product name, a post title — generateMetadata must be an async function that fetches that same data using the exact same shared data-fetching function the page component itself uses, so the request gets deduped against the page's own fetch instead of firing as a second, separate query.

PAGE TYPE AND ROUTE
A blog post detail page at /blog/[slug]

DATA SOURCE
getPost(slug) — a shared, memoized data-fetching function used by both the page component and generateMetadata

SITE DOMAIN
https://blog.example.com

INDEXING RULES
Published posts should be indexed; draft posts (reachable via a share link with ?preview=true) must never be indexed

REQUIREMENTS
Export generateMetadata as an async function accepting the same params and searchParams the page component receives, and return title, description, and openGraph fields built from the real fetched data, never placeholder text left in as a stand-in. Set metadataBase in the root layout's metadata export to the domain given above, so that relative Open Graph and Twitter image paths resolve to absolute URLs — do not hardcode the domain into every individual page's metadata export, since that duplicates a single fact across every route and drifts the moment the domain changes. Set a canonical URL per page via alternates.canonical, especially for any route reachable through more than one URL pattern, such as query-parameter variants or a trailing-slash difference, since search engines otherwise treat those as separate, competing pages. For any page that shouldn't be indexed — draft content, an internal tool, a duplicate parameterized view — set robots: { index: false } explicitly on that page's own metadata rather than relying on it being excluded from a sitemap alone, since exclusion from a sitemap doesn't stop a crawler from finding and indexing the page through some other link path. If the data fetch inside generateMetadata fails or returns nothing — a deleted product, a post that no longer exists — return sensible fallback metadata, such as a generic title paired with noindex, rather than letting the function throw and take down the entire page render over what should only affect the page's metadata.

OUTPUT FORMAT
The generateMetadata function code, plus one line confirming the fetch it makes is the exact same cached, deduped call the page component uses, named by function, and one line listing which routes on this app should be marked noindex and why each one qualifies.