Add Google Calendar link to event page

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/event.html

@@ -29,6 +29,9 @@
   {{if .DescriptionHTML}}
   <div class="event-description">{{.DescriptionHTML}}</div>
   {{end}}
+  <div style="margin-top:14px">
+    <a href="{{.GCalURL}}" target="_blank" rel="noopener" class="gcal-link">&#128197; Add to Google Calendar &#8599;</a>
+  </div>
 </div>
 
 <div id="slots-container"

templates/layout.html

@@ -132,6 +132,21 @@
     margin: 8px 0;
     color: #555;
   }
+  .gcal-link {
+    display: inline-block;
+    font-family: 'DM Mono', monospace;
+    font-size: 0.75rem;
+    color: var(--ink);
+    text-decoration: none;
+    border: 1.5px solid var(--ink);
+    padding: 5px 12px;
+    background: var(--cream);
+    transition: box-shadow 0.1s, transform 0.1s;
+  }
+  .gcal-link:hover {
+    box-shadow: 3px 3px 0 var(--ink);
+    transform: translate(-1px, -1px);
+  }
   .section-label {
     font-family: 'DM Mono', monospace;
     font-size: 0.7rem;