fix(hero): serve full-resolution carousel images

Bootstrap-3 caps slide images with `max-width: 100%` only; if the
natural image is narrower than the viewport, the slide stops short
of the column edge. The macro was downscaling to 1920 px, which made
the hero shrink on >1920 px screens.

Match live's behaviour by serving the raw source image (5345 / 5621 px
wide) without resize — the source images are intentionally oversized
for this reason.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

templates/index.html

@@ -16,7 +16,11 @@
   <div class="carousel-inner" role="listbox">
     {% for slide in section.extra.slides %}
       <div class="item{% if loop.first %} active{% endif %}">
-        {{ image::render(src=slide.image, width=1920, alt=slide.alt) }}
+        {# Serve the source image at full resolution — Bootstrap-3 only
+           constrains via `max-width: 100%`, so on viewports wider than
+           the natural image width the slide would otherwise sit short
+           of the column edge. Live does the same (no resize). #}
+        {{ image::render(src=slide.image, alt=slide.alt) }}
         <div class="carousel-caption">
           <p>{{ slide.heading }}</p>
         </div>