release: v0.13.0 (#535)

Twenty-nine commits since v0.12.0. See CHANGELOG.md for the full list
and the upgrade notes.

Ten additions — the SEO package (site URL, robots.txt, sitemap.xml,
JSON-LD), slideshow mode, opt-in original downloads, copy-link,
previous/next album navigation, alt text from the Immich description,
per-album location precision, the update notice, a Help tab, and a
subpage cover grid separate from its photo grid. Two fixes: CJK album
slugs, and the lightbox control bar.

Photo of the Day (#476) was built on `dev` and reverted as not planned;
it never appears in a release.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

https://claude.ai/code/session_01DmsHVRL9yQvckUB1ZpVWre

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: ralksta <ralksta@users.noreply.github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

app/layout.tsx

@@ -47,6 +47,10 @@ export async function generateMetadata(): Promise<Metadata> {
   };
 
   return {
+    // Without this, Next resolves Open Graph and canonical URLs against
+    // localhost. Absent when nobody configured a site URL, which leaves the
+    // previous behaviour rather than inventing a host.
+    ...(config.siteUrl ? { metadataBase: new URL(config.siteUrl) } : {}),
     title: {
       default: siteTitle,
       template: config.seo.titleTemplate,