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/public_urls.py

@@ -0,0 +1,13 @@
+from django.urls import path
+
+from events import views
+
+app_name = "events"
+
+urlpatterns = [
+    path("", views.event_list, name="list"),
+    path("order/<uuid:pk>/success/", views.checkout_success, name="checkout_success"),
+    path("order/<uuid:pk>/cancel/", views.checkout_cancel, name="checkout_cancel"),
+    path("<slug:slug>/", views.event_detail, name="detail"),
+    path("<slug:slug>/buy/", views.buy_tickets, name="buy"),
+]