ui(archiv+library): Section-Header, mehr Spalten, Kategorie-Pills

Archiv-Unterseiten (Büroführung etc.): .collection-Wrapper mit
--palette-kusa, .collection-title statt .section-header — gleiche
Optik wie Archiv/Library-Übersichten. Artikel-Grid: auto-fill
minmax(220px) → 3+ Spalten. Datum unter Titel (card-layout).

Archiv-Toggle-Pills: font-family-display (wie Dialog-Pill), margin
von spacing-md → 0.5em.

Library-Übersicht: A-Z-Index → Kategorie-Pills (Gruppe ausgeschrieben,
aktiv = ichigo), Atlas als 2-Spalten-Grid (.atlas--grid2), Suche
kombiniert mit Gruppe-Filter.

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

layouts/archiv/list.html

@@ -132,30 +132,31 @@
       </section>
 
     {{ else }}
-      {{/* Archiv-Unterseite (Rubrik): chronologisch */}}
-      {{ $section := path.Base .RelPermalink }}
-      <header class="section-header" data-section="{{ $section }}">
+      {{/* Archiv-Unterseite (Rubrik): gleiche Optik wie Übersichten */}}
+      <div class="collection" style="--section-color: var(--palette-kusa)">
         <p class="section-rubric">Archiv</p>
-        <h1 class="section-title">{{ .Title }}</h1>
-        {{ with .Params.description }}<p class="section-description">{{ . }}</p>{{ end }}
-      </header>
-      {{ .Content }}
-      <div class="time-list" data-section="{{ $section }}">
-        <ul>
-          {{ range .RegularPages.ByDate.Reverse }}
-            <li class="list-item">
-              <div class="list-title-row">
-                <div class="list-title">
-                  <a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a>
-                  {{ with .Params.summary }}
-                    <div class="list-summary text-muted">{{ . }}</div>
-                  {{ end }}
-                </div>
-                <div class="list-meta">{{ partial "date.html" .Date }}</div>
-              </div>
-            </li>
-          {{ end }}
-        </ul>
+        <h1 class="collection-title">{{ .Title }}</h1>
+        <div class="collection-inner">
+          {{ with .Params.description }}<p class="section-description">{{ . }}</p>{{ end }}
+          {{ .Content }}
+          <div class="time-list">
+            <ul>
+              {{ range .RegularPages.ByDate.Reverse }}
+                <li class="list-item">
+                  <div class="list-title-row">
+                    <div class="list-title">
+                      <a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a>
+                      {{ with .Params.summary }}
+                        <div class="list-summary text-muted">{{ . }}</div>
+                      {{ end }}
+                    </div>
+                    <div class="list-meta">{{ partial "date.html" .Date }}</div>
+                  </div>
+                </li>
+              {{ end }}
+            </ul>
+          </div>
+        </div>
       </div>
     {{ end }}
 {{ end }}