Ship the three C4 examples and model:scaffold --example

- examples/: c4-standard-web-app, c4-e-shop (was online-shop),
  c4-event-based-integration; the same models the extension offers
  under Archify | New Model…
- model-scaffold --example <name> copies one and renames id, name,
  description and the overview title; never overwrites
- tests cover every example and the copy; docs updated

examples/c4-event-based-integration/registry/containers.archify-registry

@@ -0,0 +1,40 @@
+schema_version: 1
+elements:
+  ingest:
+    type: backend
+    label: Ingest API
+    sublabel: HTTPS in, events out
+    description: Accepts events from systems that cannot publish to the bus themselves.
+  bus:
+    type: messagebus
+    label: Event bus
+    sublabel: Kafka
+    brand: apache-kafka
+    description: One topic per event type; retained for seven days.
+  router:
+    type: backend
+    label: Event router
+    sublabel: validate, enrich, dispatch
+    description: Checks each event against its schema, adds reference data, hands it to the consumers.
+    diagram: 0300-components/router.archify
+  dlq:
+    type: messagebus
+    label: Dead-letter queue
+    sublabel: failed events
+    description: Events the router could not process; replayed by operations.
+  store:
+    type: database
+    label: Event store
+    sublabel: PostgreSQL
+    brand: postgresql
+    description: Every accepted event, for audit and replay.
+  notifier:
+    type: backend
+    label: Notifier
+    sublabel: email, chat
+    description: Turns selected events into messages to people.
+  analytics:
+    type: database
+    label: Analytics
+    sublabel: warehouse tables
+    description: Flattened events for reporting.

examples/c4-event-based-integration/registry/people.archify-registry

@@ -0,0 +1,7 @@
+schema_version: 1
+elements:
+  ops:
+    type: external
+    label: Operations
+    sublabel: on-call
+    description: Watches the dead-letter queue and replays failed events.

examples/c4-event-based-integration/registry/systems.archify-registry

@@ -0,0 +1,23 @@
+schema_version: 1
+elements:
+  platform:
+    type: cloud
+    label: Integration platform
+    sublabel: the system
+    description: Receives events from the business systems, routes them, keeps a record.
+    diagram: 0200-containers/platform.archify
+  crm:
+    type: external
+    label: CRM
+    sublabel: customers
+    description: Source of customer events; created, updated, merged.
+  erp:
+    type: external
+    label: ERP
+    sublabel: orders and stock
+    description: Source of order events and the target of stock updates.
+  warehouse:
+    type: external
+    label: Warehouse system
+    sublabel: fulfilment
+    description: Receives pick lists; reports shipments back as events.