Custom post content blocks (images/gallery/video/quote) + backend-driven SEO settings

RichText.tsx switched to Payload's official React renderer + custom
JSXConverters (same call signature, LiveRichText/LivePostContent
untouched) — needed to render the new Lexical Blocks the Payload repo's
Posts.content just gained. Converters follow the existing CMS-image
convention (relative + aspect-[...] + fill + object-cover); the video
block resolves YouTube/Vimeo links to an iframe embed.

New getSeoSettings() fetcher (same pattern as getKleinunternehmer()),
app/layout.tsx now generateMetadata() reading it with the same fallback
values it used to hardcode. Per-post SEO overrides (seoTitle/
seoDescription/seoImage) wired into the blog detail page's metadata,
falling back to title/excerpt/thumbnail when empty.

Also fixed while auditing every page's metadata: missing descriptions on
3 konto pages, a static title on the dynamic order-detail route, and
missing OG images on /shop and /blog.

app/blog/page.tsx

@@ -11,6 +11,13 @@ export const metadata: Metadata = {
   title: "Blog",
   description: "Gedanken, Methoden und Impulse für einen leichteren und klareren Alltag.",
   alternates: { canonical: "/blog" },
+  openGraph: {
+    title: "Blog | einfach produktiv.",
+    description: "Gedanken, Methoden und Impulse für einen leichteren und klareren Alltag.",
+    url: "/blog",
+    type: "website",
+    images: ["/blog-featured.jpg"],
+  },
 };
 
 export default async function BlogOverviewPage() {