feat: Book cover integration — 7 covers, 3 sizes, hero + list

Process 7 source TIFFs into optimized WebP at 3 sizes (96/256/512px).
Two-column hero layout on book pages: text left, cover right, stacking
on mobile with cover above. Subtle shadow + border treatment, no
cropping, no rounded corners. Thumbnail covers (88px) on books list
page. Responsive srcset with appropriate sizes attribute.

21 new assets in /assets/books/covers/.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ThorFuchs

_layouts/publication-book.html

@@ -10,15 +10,29 @@
   {% endif %}
 {% endfor %}
 
-<div class="hero-card">
-  <span class="eyebrow">Publications · Books</span>
-  <h1>{{ page.title }}</h1>
-  {% if page.subtitle %}
-  <p class="hero-subtitle">{{ page.subtitle }}</p>
-  {% endif %}
-  {% if page.summary_short and page.summary_short != page.subtitle %}
-  <p>{{ page.summary_short }}</p>
-  {% endif %}
+{% assign cover_path = '/assets/books/covers/' | append: page.book_slug | append: '-cover-' %}
+
+<div class="hero-card book-hero">
+  <div class="book-hero-inner">
+    <div class="book-hero-text">
+      <span class="eyebrow">Publications · Books</span>
+      <h1>{{ page.title }}</h1>
+      {% if page.subtitle %}
+      <p class="hero-subtitle">{{ page.subtitle }}</p>
+      {% endif %}
+    </div>
+    <div class="book-hero-cover">
+      <img
+        src="{{ cover_path | append: '256.webp' | relative_url }}"
+        srcset="{{ cover_path | append: '256.webp' | relative_url }} 256w, {{ cover_path | append: '512.webp' | relative_url }} 512w"
+        sizes="(max-width: 760px) min(72vw, 260px), 240px"
+        width="256" height="410"
+        alt="Cover of {{ page.title }}: {{ page.subtitle }}"
+        class="book-cover-img"
+        loading="eager"
+      >
+    </div>
+  </div>
 </div>
 
 {% include summary-cards.html %}

_sass/_components.scss

@@ -145,6 +145,97 @@
   margin-top: 4px;
 }
 
+// ================================================================
+// Book Cover Hero (two-column layout)
+// ================================================================
+
+.book-hero-inner {
+  display: flex;
+  gap: 28px;
+  align-items: flex-start;
+
+  @media (max-width: $bp-stack) {
+    flex-direction: column;
+    align-items: center;
+    text-align: center;
+  }
+}
+
+.book-hero-text {
+  flex: 1;
+  min-width: 0;
+}
+
+.book-hero-cover {
+  flex-shrink: 0;
+  width: 240px;
+
+  @media (max-width: $bp-collapse) {
+    width: 200px;
+  }
+
+  @media (max-width: $bp-stack) {
+    width: min(72vw, 260px);
+    order: -1; // cover above text on mobile
+  }
+}
+
+.book-cover-img {
+  width: 100%;
+  height: auto;
+  display: block;
+  border-radius: 6px;
+  box-shadow:
+    0 4px 16px rgba(22, 29, 37, 0.10),
+    0 1px 4px rgba(22, 29, 37, 0.06);
+  border: 1px solid rgba(0, 0, 0, 0.06);
+}
+
+// Book list thumbnails
+.book-list-thumb {
+  width: 88px;
+  height: auto;
+  border-radius: 4px;
+  box-shadow: 0 2px 8px rgba(22, 29, 37, 0.08);
+  border: 1px solid rgba(0, 0, 0, 0.05);
+  flex-shrink: 0;
+}
+
+.book-list-item {
+  display: flex;
+  gap: 16px;
+  align-items: flex-start;
+  padding: 12px 0;
+  border-bottom: 1px solid $divider;
+
+  &:last-child { border-bottom: none; }
+
+  .book-list-info {
+    flex: 1;
+    min-width: 0;
+
+    h3 {
+      font-family: $font-display;
+      font-size: 1rem;
+      font-weight: 500;
+      margin: 0 0 4px;
+
+      a {
+        color: $text;
+        text-decoration: none;
+        &:hover { color: $accent; }
+      }
+    }
+
+    p {
+      font-size: 0.86rem;
+      color: $text-muted;
+      margin: 0;
+      line-height: 1.45;
+    }
+  }
+}
+
 // ================================================================
 // Format Cards (Amazon book formats)
 // ================================================================