Add markdown event descriptions for hosts to provide context

Hosts can now add a free-form description (with markdown rendering via
goldmark) when creating or editing events. Descriptions render safely
with no raw HTML passthrough. Includes ALTER TABLE migration for
existing databases.

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

templates/event.html

@@ -26,6 +26,9 @@
     {{if .Event.Time}}<span>&#128338; {{.Event.Time}}</span>{{end}}
     {{if .Event.Location}}<span>&#128205; {{.Event.Location}}</span>{{end}}
   </div>
+  {{if .DescriptionHTML}}
+  <div class="event-description">{{.DescriptionHTML}}</div>
+  {{end}}
 </div>
 
 <div id="slots-container"
@@ -87,6 +90,17 @@
 {{end}}
 
 {{if .IsAdmin}}
+<div class="section-label" style="margin-top:40px">Admin: Description</div>
+<div class="claim-form-wrapper">
+  <form method="POST" action="/e/{{.Event.Slug}}/admin/{{.Event.AdminToken}}/description">
+    <div class="form-row">
+      <label>Event description (markdown supported)</label>
+      <textarea name="description" rows="5" style="border:var(--border-w) solid var(--border);background:var(--cream);padding:10px 14px;font-family:'Bricolage Grotesque',sans-serif;font-size:0.95rem;resize:vertical;outline:none;">{{.Event.Description}}</textarea>
+    </div>
+    <button class="btn-submit" type="submit">Save description</button>
+  </form>
+</div>
+
 <div class="section-label" style="margin-top:40px">Admin: Add slot</div>
 <div class="claim-form-wrapper">
   <form hx-post="/e/{{.Event.Slug}}/admin/{{.Event.AdminToken}}/slot"

templates/home.html

@@ -29,6 +29,10 @@
       <label>Location</label>
       <input type="text" name="location" placeholder="e.g. Long Meadow, entrance at 9th St">
     </div>
+    <div class="form-row">
+      <label>Description (optional, markdown supported)</label>
+      <textarea name="description" rows="4" placeholder="e.g. Bring your own blanket! We'll have a grill set up near the big oak tree." style="border:var(--border-w) solid var(--border);background:var(--cream);padding:10px 14px;font-family:'Bricolage Grotesque',sans-serif;font-size:0.95rem;resize:vertical;outline:none;"></textarea>
+    </div>
 
     <div class="section-label" style="margin:24px 0 16px">Slots</div>
 

templates/layout.html

@@ -97,6 +97,41 @@
     font-size: 0.78rem;
     color: #555;
   }
+  .event-description {
+    margin-top: 16px;
+    padding-top: 16px;
+    border-top: 1px solid #ddd;
+    font-size: 0.92rem;
+    line-height: 1.6;
+  }
+  .event-description h1 { font-size: 1.3rem; margin: 16px 0 8px; }
+  .event-description h2 { font-size: 1.15rem; margin: 14px 0 6px; }
+  .event-description h3 { font-size: 1.05rem; margin: 12px 0 4px; }
+  .event-description p { margin: 8px 0; }
+  .event-description ul, .event-description ol { margin: 8px 0; padding-left: 24px; }
+  .event-description li { margin: 4px 0; }
+  .event-description a { color: var(--ink); text-decoration: underline; }
+  .event-description code {
+    font-family: 'DM Mono', monospace;
+    background: var(--cream);
+    padding: 2px 6px;
+    font-size: 0.85em;
+    border: 1px solid #ddd;
+  }
+  .event-description pre {
+    background: var(--cream);
+    border: 1px solid #ddd;
+    padding: 12px;
+    overflow-x: auto;
+    margin: 8px 0;
+  }
+  .event-description pre code { background: none; border: none; padding: 0; }
+  .event-description blockquote {
+    border-left: 3px solid var(--ink);
+    padding-left: 12px;
+    margin: 8px 0;
+    color: #555;
+  }
   .section-label {
     font-family: 'DM Mono', monospace;
     font-size: 0.7rem;
@@ -230,7 +265,7 @@
     transition: box-shadow 0.1s;
     appearance: none;
   }
-  .form-row input:focus, .form-row select:focus {
+  .form-row input:focus, .form-row select:focus, .form-row textarea:focus {
     box-shadow: 3px 3px 0 var(--ink);
   }
   .btn-submit {