Add shop, POS sync, event ticketing, and shipping catalog apps.

Clients can run in-house retail without Shopify while keeping the same
Docker/Django/Postgres stack and data-ownership promise. Closes #5.

site/events/hooks.py

@@ -0,0 +1,33 @@
+from core.registry import (
+    register_dashboard_collector,
+    register_feature,
+    register_portal_nav,
+    register_public_nav,
+)
+
+
+def register() -> None:
+    register_feature("events")
+    register_public_nav(
+        section="events", label="Events", url_name="events:list", order=35
+    )
+    register_portal_nav(
+        section="events",
+        label="Events",
+        url_name="events_portal:event_list",
+        group="Retail",
+        order=30,
+    )
+    register_dashboard_collector(_dashboard)
+
+
+def _dashboard(request) -> dict:
+    from django.utils import timezone
+
+    from events.models import Event
+
+    return {
+        "upcoming_events": Event.objects.filter(
+            is_published=True, starts_at__gte=timezone.now()
+        ).count()
+    }