Monorepo: consolidate 7 repos into one

Combines shared, blog, market, cart, events, federation, and account
into a single repository. Eliminates submodule sync, sibling model
copying at build time, and per-app CI orchestration.

Changes:
- Remove per-app .git, .gitmodules, .gitea, submodule shared/ dirs
- Remove stale sibling model copies from each app
- Update all 6 Dockerfiles for monorepo build context (root = .)
- Add build directives to docker-compose.yml
- Add single .gitea/workflows/ci.yml with change detection
- Add .dockerignore for monorepo build context
- Create __init__.py for federation and account (cross-app imports)

events/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 %}