Merge remote-tracking branch 'origin/main' into feature/ai-search

# Conflicts:
#	.env
#	components/Header.tsx
#	components/home/Hero.tsx

app/[locale]/blog/[slug]/opengraph-image.tsx

@@ -8,6 +8,20 @@ export const size = OG_IMAGE_SIZE;
 export const contentType = 'image/png';
 export const runtime = 'nodejs';
 
+async function fetchImageAsBase64(url: string) {
+  try {
+    const res = await fetch(url);
+    if (!res.ok) return undefined;
+    const arrayBuffer = await res.arrayBuffer();
+    const buffer = Buffer.from(arrayBuffer);
+    const contentType = res.headers.get('content-type') || 'image/jpeg';
+    return `data:${contentType};base64,${buffer.toString('base64')}`;
+  } catch (error) {
+    console.error('Failed to fetch OG image:', url, error);
+    return undefined;
+  }
+}
+
 export default async function Image({
   params,
 }: {
@@ -32,12 +46,19 @@ export default async function Image({
       : `${SITE_URL}${post.frontmatter.featuredImage}`
     : undefined;
 
+  // Fetch image explicitly and convert to base64 because Satori sometimes struggles
+  // fetching remote URLs directly inside ImageResponse correctly in various environments.
+  let base64Image: string | undefined = undefined;
+  if (featuredImage) {
+    base64Image = await fetchImageAsBase64(featuredImage);
+  }
+
   return new ImageResponse(
     <OGImageTemplate
       title={post.frontmatter.title}
       description={post.frontmatter.excerpt}
       label={post.frontmatter.category || 'Blog'}
-      image={featuredImage}
+      image={base64Image || featuredImage}
     />,
     {
       ...OG_IMAGE_SIZE,

app/[locale]/blog/[slug]/page.tsx

@@ -1,12 +1,18 @@
 import { notFound, redirect } from 'next/navigation';
 import JsonLd from '@/components/JsonLd';
 import { SITE_URL } from '@/lib/schema';
-import { getPostBySlug, getAdjacentPosts, getReadingTime } from '@/lib/blog';
+import {
+  getPostBySlug,
+  getAdjacentPosts,
+  getReadingTime,
+  extractLexicalHeadings,
+} from '@/lib/blog';
 import { Metadata } from 'next';
 import Link from 'next/link';
 import Image from 'next/image';
 import PostNavigation from '@/components/blog/PostNavigation';
 import PowerCTA from '@/components/blog/PowerCTA';
+import TableOfContents from '@/components/blog/TableOfContents';
 import { Heading } from '@/components/ui';
 import { setRequestLocale } from 'next-intl/server';
 import BlogEngagementTracker from '@/components/analytics/BlogEngagementTracker';
@@ -67,6 +73,10 @@ export default async function BlogPost({ params }: BlogPostProps) {
 
   const { prev, next, isPrevRandom, isNextRandom } = await getAdjacentPosts(post.slug, locale);
 
+  // Convert Lexical content into a plain string to estimate reading time roughly
+  // Extract headings for TOC
+  const headings = extractLexicalHeadings(post.content?.root || post.content);
+
   // Convert Lexical content into a plain string to estimate reading time roughly
   const rawTextContent = JSON.stringify(post.content);
 
@@ -88,6 +98,7 @@ export default async function BlogPost({ params }: BlogPostProps) {
               alt={post.frontmatter.title}
               fill
               priority
+              quality={100}
               className="object-cover"
               sizes="100vw"
               style={{
@@ -113,7 +124,7 @@ export default async function BlogPost({ params }: BlogPostProps) {
                 </Heading>
                 <div className="flex flex-wrap items-center gap-6 text-white/80 text-sm md:text-base font-medium">
                   <time dateTime={post.frontmatter.date} suppressHydrationWarning>
-                    {new Date(post.frontmatter.date).toLocaleDateString(locale, {
+                    {new Date(post.frontmatter.date).toLocaleDateString(locale || 'de', {
                       year: 'numeric',
                       month: 'long',
                       day: 'numeric',
@@ -150,7 +161,7 @@ export default async function BlogPost({ params }: BlogPostProps) {
             </Heading>
             <div className="flex items-center gap-6 text-text-primary/80 font-medium">
               <time dateTime={post.frontmatter.date} suppressHydrationWarning>
-                {new Date(post.frontmatter.date).toLocaleDateString(locale, {
+                {new Date(post.frontmatter.date).toLocaleDateString(locale || 'de', {
                   year: 'numeric',
                   month: 'long',
                   day: 'numeric',
@@ -231,10 +242,10 @@ export default async function BlogPost({ params }: BlogPostProps) {
             </div>
           </div>
 
-          {/* Right Column: Sticky Sidebar - Temporarily Hidden without ToC */}
+          {/* Right Column: Sticky Sidebar - TOC */}
           <aside className="sticky-narrative-sidebar hidden lg:block">
-            <div className="space-y-12">
-              {/* Future Payload Table of Contents Implementation */}
+            <div className="space-y-12 lg:sticky lg:top-32">
+              <TableOfContents headings={headings} locale={locale} />
             </div>
           </aside>
         </div>

app/[locale]/blog/page.tsx

@@ -198,7 +198,7 @@ export default async function BlogIndex({ params }: BlogIndexProps) {
 
                       <div className="flex items-center gap-3 text-xs md:text-sm font-bold text-white/80 mb-3 tracking-widest uppercase">
                         <time dateTime={post.frontmatter.date} suppressHydrationWarning>
-                          {new Date(post.frontmatter.date).toLocaleDateString(locale, {
+                          {new Date(post.frontmatter.date).toLocaleDateString(locale || 'de', {
                             year: 'numeric',
                             month: 'long',
                             day: 'numeric',