Add complete Open Graph metadata layer across all 20 pages

- Add og:title, og:description, og:image, og:url, og:type, og:site_name to BaseLayout
- Add og:locale (en_GB) + og:locale:alternate (fr_FR, nb_NO) multilingual signals
- Add article:published_time, article:section, article:author on all 5 article pages
- Add Twitter/X summary_large_image card and canonical link on every page
- Generate 13 Jazz Noir branded 1200x630 PNG OG images (satori + resvg-js)
- Add scripts/generate-og-images.mjs + Special Elite font for future regeneration
- Add public/images/articles/ and public/assets/ which were previously untracked

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/pages/articles/kongsberg-jazz-2026.astro

@@ -42,6 +42,10 @@ const pageCopy = {
 <BaseLayout
   title={`${jazzArticle.title} | Dave Gilligan`}
   description={jazzArticle.excerpt.en}
+  ogType="article"
+  ogImage="/images/og/jazz-music.png"
+  ogArticlePublishedTime={jazzArticle.publishedAt.replace(' ', 'T') + 'Z'}
+  ogArticleSection="Jazz and Music"
 >
   <main class="jazz-page">
     <section class="container jazz-hero">