feat(news): add Meet Student Slovenia 2026 event page

Trilingual (EN/MK/SI) promo page for the upcoming "Meet Student Slovenia
2026" event, built through the content CMS (content/news/...) plus custom
sections styled to match the site.

- Guide-style centred header with a wide banner hero and caption
- Plain-background key facts (When/Where), subtle live-stream line,
  centred Register CTA, and partner/patron/sponsor logos
  (NLB Banka, Embassy of Slovenia; Capital Financial Center as text)
- Auto-scrolling "Moments from previous years" carousel + inline photos
- Embedded registration form (dropdowns, required study-plan fields,
  multi-field study preferences) wired to a Google Form; left-hand
  floating Register button
- Homepage promo banner (EN/MK/SI) + auto-listed in News hub, homepage
  latest, sitemap, llms.txt and the offline search index
- New assets: css/pages/_event.css, event-register.js

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

css/main.css

@@ -44,6 +44,7 @@
 @import 'pages/_legal.css';
 @import 'pages/_gallery.css';
 @import 'pages/_press.css';
+@import 'pages/_event.css';
 
 /* Loaded last so the shared filter bar wins over per-page chip styles. */
 @import 'pages/_filterbar.css';