Content cleanup: fix unclosed tags, remove em/en dashes, verify translations

- Fixed 3 SI event posts that were missing their </article> and </main> tags
- Replaced all punctuation em-dashes and spaced en-dashes (435 across 64 files)
  with commas; normalized a SI date range to a hyphen to match EN/MK
- Verified the new Gallery + in-post gallery content is fully translated in
  EN/MK/SI (headings, titles, links, nav labels) with no English leftovers

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

en/blog/how-to-open-slovenian-bank-account/index.html

@@ -348,7 +348,7 @@
             <div class="container">
                 <div class="cta-content">
                     <h2>Never miss an MSOS update</h2>
-                    <p>News, announcements and open calls — straight to your inbox.</p>
+                    <p>News, announcements and open calls, straight to your inbox.</p>
                     <form class="subscribe-form-bottom">
                          <div class="input-wrapper">
                             <input type="email" placeholder="Enter your email">