fix(seo): add endDate, performer, offers to Event structured data

Clears the 3 non-critical Events issues in Search Console
("Missing field endDate/performer/offers") across all /projects/
recap pages. These are free, single-day events, so endDate mirrors
startDate, performer is MSOS (host org), and offers is a zero-price
Offer. Generated centrally in tools/seo_inject.py and re-injected.

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

si/blog/welcome-days-slovenian-universities-2026-2027/index.html

@@ -21,7 +21,7 @@
       gtag('js', new Date());
       gtag('config', 'G-WVYV807VSS');
     </script>
-    <script src="/consent.js?v=f95de694" defer></script>
+    <script src="/consent.js" defer></script>
     <meta name="description" content="Začetek študija v drugi državi je lažji, če veste, kam morate priti, koga lahko vprašate in kaj se bo dogajalo v prvih dneh. Glavne slovenske univerze…">
     <link rel="canonical" href="https://msosorg.com/si/blog/welcome-days-slovenian-universities-2026-2027/">
     <link rel="alternate" hreflang="en" href="https://msosorg.com/en/blog/welcome-days-slovenian-universities-2026-2027/">