feat: display photos on /photos/ listing page

- Render photo frontmatter as actual img tags
- Add photo gallery CSS with responsive grid
- Support multi-photo posts with 2-column grid
- Add photo caption styling

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

photos.njk

@@ -9,7 +9,7 @@ permalink: /photos/
 </div>
 
 {% if collections.photos.length > 0 %}
-<ul class="post-list">
+<ul class="post-list photo-list">
   {% for post in collections.photos %}
   <li class="h-entry">
     <div class="post-meta">
@@ -17,7 +17,19 @@ permalink: /photos/
         {{ post.date | dateDisplay }}
       </time>
     </div>
-    <div class="e-content">{{ post.templateContent | safe }}</div>
+    {# Render photo(s) from frontmatter #}
+    {% if post.data.photo %}
+      <div class="photo-gallery">
+        {% for img in post.data.photo %}
+          <a href="{{ post.url }}" class="photo-link">
+            <img src="{{ img.url }}" alt="{{ img.alt | default('Photo') }}" class="u-photo" loading="lazy">
+          </a>
+        {% endfor %}
+      </div>
+    {% endif %}
+    {% if post.templateContent %}
+    <div class="e-content photo-caption">{{ post.templateContent | safe }}</div>
+    {% endif %}
   </li>
   {% endfor %}
 </ul>