Phase 4: add container-nav/cards fragment handlers, use market fragment

Events provides container-nav (calendar entries + links) and
container-cards (batch entries for blog listing) as fragments.
Day and entry routes fetch market container-nav via fragment instead
of widget registry.

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

templates/fragments/container_cards_entries.html

@@ -0,0 +1,33 @@
+{# Calendar entries for blog listing cards — served as fragment from events app.
+   Each post's entries are delimited by comment markers so the consumer can
+   extract per-post HTML via simple string splitting. #}
+{% for post_id in post_ids %}
+<!-- card-widget:{{ post_id }} -->
+{% set widget_entries = batch.get(post_id, []) %}
+{% if widget_entries %}
+<div class="mt-4 mb-2">
+  <h3 class="text-sm font-semibold text-stone-700 mb-2 px-2">Events:</h3>
+  <div class="overflow-x-auto scrollbar-hide" style="scroll-behavior: smooth;">
+    <div class="flex gap-2 px-2">
+      {% for entry in widget_entries %}
+        {% set _post_slug = slug_map.get(post_id, '') %}
+        {% set _entry_path = '/' + _post_slug + '/calendars/' + entry.calendar_slug + '/' + entry.start_at.year|string + '/' + entry.start_at.month|string + '/' + entry.start_at.day|string + '/entries/' + entry.id|string + '/' %}
+        <a
+          href="{{ events_url(_entry_path) }}"
+          class="flex flex-col gap-1 px-3 py-2 bg-stone-50 hover:bg-stone-100 rounded border border-stone-200 transition text-sm whitespace-nowrap flex-shrink-0 min-w-[180px]">
+          <div class="font-medium text-stone-900 truncate">{{ entry.name }}</div>
+          <div class="text-xs text-stone-600">
+            {{ entry.start_at.strftime('%a, %b %d') }}
+          </div>
+          <div class="text-xs text-stone-500">
+            {{ entry.start_at.strftime('%H:%M') }}
+            {% if entry.end_at %} – {{ entry.end_at.strftime('%H:%M') }}{% endif %}
+          </div>
+        </a>
+      {% endfor %}
+    </div>
+  </div>
+</div>
+{% endif %}
+<!-- /card-widget:{{ post_id }} -->
+{% endfor %}

templates/fragments/container_nav_calendars.html

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+{# Calendar links nav — served as fragment from events app #}
+{% for calendar in calendars %}
+  {% set local_href=events_url('/' + post_slug + '/calendars/' + calendar.slug + '/') %}
+  <a
+    href="{{ local_href }}"
+    class="{{styles.nav_button_less_pad}}">
+    <i class="fa fa-calendar" aria-hidden="true"></i>
+    <div>{{calendar.name}}</div>
+  </a>
+{% endfor %}

templates/fragments/container_nav_entries.html

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+{# Calendar entries nav — served as fragment from events app #}
+{% for entry in entries %}
+  {% set _entry_path = '/' + post_slug + '/calendars/' + entry.calendar_slug + '/' + entry.start_at.year|string + '/' + entry.start_at.month|string + '/' + entry.start_at.day|string + '/entries/' + entry.id|string + '/' %}
+  <a
+    href="{{ events_url(_entry_path) }}"
+    class="{{styles.nav_button_less_pad}}"
+  >
+    <div class="w-8 h-8 rounded bg-stone-200 flex-shrink-0"></div>
+    <div class="flex-1 min-w-0">
+      <div class="font-medium truncate">{{ entry.name }}</div>
+      <div class="text-xs text-stone-600 truncate">
+        {{ entry.start_at.strftime('%b %d, %Y at %H:%M') }}
+        {% if entry.end_at %} – {{ entry.end_at.strftime('%H:%M') }}{% endif %}
+      </div>
+    </div>
+  </a>
+{% endfor %}
+
+{# Infinite scroll sentinel — URL points back to the consumer app #}
+{% if has_more and paginate_url_base %}
+  <div id="entries-load-sentinel-{{ page }}"
+       hx-get="{{ paginate_url_base }}?page={{ page + 1 }}"
+       hx-trigger="intersect once"
+       hx-swap="beforebegin"
+       _="on htmx:afterRequest trigger scroll on #associated-entries-container"
+       class="flex-shrink-0 w-1">
+  </div>
+{% endif %}