fix: use Nunjucks-compatible syntax for URL check

photos.njk

@@ -21,7 +21,10 @@ permalink: /photos/
     {% if post.data.photo %}
       <div class="photo-gallery">
         {% for img in post.data.photo %}
-          {% set photoUrl = img.url if img.url.startsWith('/') or img.url.startsWith('http') else '/' + img.url %}
+          {% set photoUrl = img.url %}
+          {% if photoUrl and photoUrl[0] != '/' and 'http' not in photoUrl %}
+            {% set photoUrl = '/' + photoUrl %}
+          {% endif %}
           <a href="{{ post.url }}" class="photo-link">
             <img src="{{ photoUrl }}" alt="{{ img.alt | default('Photo') }}" class="u-photo" loading="lazy">
           </a>