Follow Products.description consolidation to richText-only

Backend dropped the plain-text description field in favor of a single
richText one (see docker/payload commit 1ba8d07). Renders formatted
(bold/italic/multiple paragraphs) via the shared RichText component on
the PDP (der-eine, tasse-die-pause); everywhere else (Passend-dazu cards,
Product JSON-LD, homepage spotlight fallback) derives plain text at read
time via a new extractPlainText() helper instead of a second field.
Removes the description line from cart line items entirely — it only
bloated the cart with no real benefit there.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J1Hu5bZ1kZUgKhab6yNwCt

app/blog/[slug]/page.tsx

@@ -162,7 +162,7 @@ export default async function BlogDetailPage({
                     >
                       {post.relatedProduct.name}
                     </p>
-                    <p className="text-[0.9375rem] text-text-muted leading-[1.45]">{post.relatedProduct.description}</p>
+                    <p className="text-[0.9375rem] text-text-muted leading-[1.45]">{post.relatedProduct.descriptionText}</p>
                   </div>
                   <span className="flex items-center gap-1.5 font-bold text-[0.875rem] text-text-primary whitespace-nowrap mt-1 sm:mt-0">
                     Entdecken