Add Support MSOS page (EN/MK/SI) and wire the header button

New donation/partnership landing page telling the MSOS story of being
community-built: hero, "built by the community" narrative, four ways to
support (partner/sponsor, donate, offer skills/space, spread the word),
"where your support goes" impact, a bank-transfer card (placeholder IBAN/
bank/SWIFT for the org to fill in), a partners thank-you marquee, and a
contact CTA (mailto info@msosorg.com). New css/pages/_support.css.

The header "Support MSOS" button (previously a dead <button>) now links to
/{lang}/support/ on all pages. SEO block + hreflang + sitemap regenerated.

MK/SI translations are AI-drafted -> native review. Bank details are
placeholders pending real IBAN/SWIFT.

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

si/index.html

@@ -102,7 +102,7 @@
             </nav>
             <div class="navigation-actions">
                 <a href="../si/become-a-member/" class="btn btn-secondary">Postani član</a>
-                <button class="btn btn-primary">Podpri MSOS ❤️</button>
+                <a href="../si/support/" class="btn btn-primary">Podpri MSOS ❤️</a>
                 <div class="language-selector">
                     <div class="current-lang">
                         <i class="fas fa-globe"></i>
@@ -159,7 +159,7 @@
     </nav>
     <div class="navigation-actions">
         <a href="../si/become-a-member/" class="btn btn-secondary">Postani član</a>
-        <button class="btn btn-primary">Podpri MSOS ❤️</button>
+        <a href="../si/support/" class="btn btn-primary">Podpri MSOS ❤️</a>
         <div class="language-selector">
             <button class="current-lang" id="mobile-lang-trigger">
                 <i class="fas fa-globe"></i>