refactor: standardize all Hugo templates — consistent landmark structure

All templates now follow: body > nav > article > header + content + footer

Removed:
- <hgroup> (redundant, header+h1+p serves same purpose)
- <main> (article is the content landmark)
- role="main" on article (incorrect ARIA)
- header block in baseof (header now inside article)

Standardized: default, docs, essay, notes, console, page, list, index.

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

site/layouts/index.html

@@ -1,28 +1,26 @@
-{{ define "title" }}{{ .Site.Title }}{{ end }}
-
-{{ define "header" }}
-  <header>
-    <hgroup>
+{{ define "content" }}
+  <article>
+    <header>
       <h1>{{ .Site.Title }}</h1>
       <p>{{ .Site.Params.description | default "An agent-first approach to web generation." }}</p>
-    </hgroup>
-  </header>
-{{ end }}
+    </header>
+
+    {{ .Content }}
 
-{{ define "content" }}
-  <article role="main">
     <section>
       <h2>Recent</h2>
       {{ range first 10 .Site.RegularPages }}
       <article>
         <header>
           <h3><a href="{{ .Permalink }}">{{ .Title }}</a></h3>
+          {{- if not .Date.IsZero }}
           <p data-text="dim">
             <time datetime="{{ .Date.Format "2006-01-02" }}">{{ .Date.Format "January 2006" }}</time>
-            {{ with .Params.eyebrow }} · {{ . }}{{ end }}
+            {{- with .Params.eyebrow }} · {{ . }}{{ end }}
           </p>
+          {{- end }}
         </header>
-        {{ with .Summary }}<p>{{ . }}</p>{{ end }}
+        {{- with .Description }}<p>{{ . }}</p>{{ end }}
       </article>
       {{ end }}
     </section>