fix(news): give MSS 2026 a card excerpt / meta description

The Meet Student Slovenia 2026 news card had an empty description because the
auto-extractor looks for the first <p> right after .news-article-body, but that
page starts with the sticky-CTA <a>, so nothing matched. Add a curated
description (EN/MK/SI) via seo_inject DESC_OVERRIDES; this now fills the meta
description, OG/Twitter/JSON-LD, the News-hub card excerpt, and llms.txt.
MK/SI copy AI-drafted — flag for native review.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

si/news/index.html

@@ -213,7 +213,7 @@
                     <div class="newshub-body">
                         <p class="newshub-date">20. avgust 2026</p>
                         <h3><a href="/si/news/meet-student-slovenia-2026/">Spoznaj študentsko Slovenijo 2026</a></h3>
-                        <p class="newshub-excerpt"></p>
+                        <p class="newshub-excerpt">Bodoči študenti in starši se pogovorijo z makedonskimi študenti, ki že študirajo v Sloveniji. Spoznaj študentsko Slovenijo 2026 — 4. septembra v Skopju in na spletu.</p>
                     </div>
                 </article>
                 <article class="newshub-card" data-type="blog">