content: add real photos + captions to all Student Welcome Guide pages

Replace the "Image placeholder" boxes on all 30 guide subpages + the guide
landing hero with real, optimized photos and captions, EN/MK/SI (93 figures).

- 31 source photos (up to 18 MB) optimized to WebP (<=1400px, all <500 KB)
  as images/guide-<slug>.webp.
- Captions follow the Get-to-Know style: description + "Photo:/Фото:/Foto:"
  + linked source (or MSOS for own event photos). Photographer credits kept.
  MK/SI descriptions are translated (proofread welcome).
- CSS: move the banner crop from the figure onto the <img> so the caption
  shows below it (was clipped by the figure's fixed height + overflow).

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

en/student-welcome-guide/index.html

@@ -195,8 +195,9 @@
             <span class="guide-eyebrow">Student Welcome Guide</span>
             <h1>From Macedonia to Slovenia, step by step</h1>
             <p class="guide-lead">Your complete route from a Macedonian secondary school or first degree to enrolled student life in Slovenia.</p>
-            <figure class="guide-hero-image guide-hero-image--placeholder">
-                <span><i class="fas fa-image" aria-hidden="true"></i>Image placeholder</span>
+            <figure class="guide-hero-image">
+                <img width="1400" height="933" fetchpriority="high" decoding="async" src="../../images/guide-hero.webp" alt="Macedonian students in Slovenia.">
+                <figcaption>Macedonian students in Slovenia. Photo: MSOS</figcaption>
             </figure>
                 <p>Moving to Slovenia for a bachelor or master degree involves more than one university application. You need to choose the correct programme, submit an application through eVŠ, complete recognition of your previous education, arrange residence and health documentation, find accommodation, travel to the right city, enrol, and activate the services connected with student status.</p>
                 <p>This guide brings those steps together for Macedonian students and families.</p>