feat: 3-column layout with centered results and right column

- results-layout: 3-column grid (1fr | min(768px,100%) | 300px) max-width 1400px, centered
- Widen center results column to 768px max
- Right column (formerly sidebar): sticky, contains knowledge panel + related searches
- Knowledge panel: Wikipedia/infobox summary with optional thumbnail
- Related searches: clickable links to refine the query
- Empty left buffer creates balanced whitespace on large screens
- Responsive: 2-col at 1000px, 1-col at 700px

internal/views/static/css/kafka.css

@@ -235,11 +235,22 @@ main {
   padding-top: 1.5rem;
 }
 
+/* 3-column layout: empty left buffer | center results | right column
+   max-width 1400px, centered on page */
 .results-layout {
   display: grid;
-  grid-template-columns: 1fr 220px;
+  grid-template-columns: 1fr min(768px, 100%) 300px;
   gap: 2rem;
   align-items: start;
+  max-width: 1400px;
+  margin: 0 auto;
+}
+
+@media (max-width: 1000px) {
+  .results-layout {
+    grid-template-columns: 1fr 260px;
+    gap: 1.5rem;
+  }
 }
 
 @media (max-width: 700px) {
@@ -249,7 +260,7 @@ main {
   }
 }
 
-/* Compact search bar on results page */
+/* Compact search bar spans all columns */
 .search-compact {
   grid-column: 1 / -1;
 }
@@ -380,12 +391,15 @@ main {
 }
 
 /* ============================================================
-   Sidebar
+   Right Column (formerly sidebar)
    ============================================================ */
 
-.sidebar {
+.right-column {
   position: sticky;
   top: calc(var(--header-height) + 1.5rem);
+  display: flex;
+  flex-direction: column;
+  gap: 1rem;
 }
 
 .sidebar-card {
@@ -393,18 +407,65 @@ main {
   border: 1px solid var(--border);
   border-radius: var(--radius-md);
   padding: 1rem;
-  margin-bottom: 1rem;
 }
 
-.sidebar-title {
-  font-size: 0.75rem;
+.sidebar-card-title {
+  font-size: 0.7rem;
   font-weight: 600;
   text-transform: uppercase;
-  letter-spacing: 0.05em;
+  letter-spacing: 0.06em;
   color: var(--text-muted);
   margin-bottom: 0.75rem;
 }
 
+/* Knowledge Panel card */
+.knowledge-panel {
+  background: var(--bg-secondary);
+  border: 1px solid var(--border);
+  border-radius: var(--radius-md);
+  padding: 1rem;
+}
+
+.knowledge-panel-title {
+  font-size: 1rem;
+  font-weight: 600;
+  color: var(--text-primary);
+  margin-bottom: 0.5rem;
+}
+
+.knowledge-panel-content {
+  font-size: 0.875rem;
+  color: var(--text-secondary);
+  line-height: 1.55;
+}
+
+.knowledge-panel-thumb {
+  width: 100%;
+  border-radius: var(--radius-sm);
+  margin-bottom: 0.75rem;
+}
+
+/* Related searches */
+.related-searches {
+  display: flex;
+  flex-direction: column;
+  gap: 0.35rem;
+}
+
+.related-search-link {
+  font-size: 0.85rem;
+  color: var(--accent);
+  text-decoration: none;
+  padding: 0.25rem 0;
+  border-radius: var(--radius-sm);
+  transition: color 0.15s;
+}
+
+.related-search-link:hover {
+  color: var(--accent-hover);
+  text-decoration: underline;
+}
+
 /* Suggestions in sidebar */
 .suggestion-list {
   display: flex;