Fix legal-page autolink color, add Blog breadcrumb, revert breadcrumb color

- RichText.tsx: Lexical's auto-detected "autolink" nodes (a typed-out
  email/URL, as opposed to an editor-inserted link) fell through to
  Payload's unstyled default converter — only "link" was overridden.
  AGB's Vertragspartner email rendered as plain black text because of
  this. Both node types now get the same text-brand/hover:underline
  treatment.
- Breadcrumb color revert: the breadcrumb Startseite links across the
  4 legal pages/shop should stay their original hover:text-brand
  treatment — only the actual content/contact links needed the
  always-brand-colored style, not page-level breadcrumbs.
- /blog was the one page missing both a breadcrumb and the
  text-h-feature heading size every other section page (/shop, legal
  pages) already uses — added to match.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018unaXmuzVA8ct1b6WoyP1U

app/datenschutz/page.tsx

@@ -26,7 +26,7 @@ export default async function DatenschutzPage() {
       <main className="flex flex-col flex-1 bg-bg-base">
         <Reveal className="flex flex-col gap-3 items-start pb-6 pt-10 px-[var(--layout-padding-x)] w-full">
           <p className="flex items-center gap-2 text-body-sm text-text-muted">
-            <Link href="/" className="text-brand hover:underline">Startseite</Link>
+            <Link href="/" className="hover:text-brand transition-colors">Startseite</Link>
             <span>›</span>
             <span className="text-text-primary">Datenschutz</span>
           </p>