feat(11.1-04): add the Database section and the core Services pages

- docs/database: models, migrations, queries and pagination, relations,
  casts and validation, attachments and transactions (lagoon.Transaction,
  lagoon.AfterCommit, nested savepoints, lagoon.OnDatabase)
- docs/services: configuration, events, routing with auth groups, rate
  limiting, authentication, the OAuth server, mail and localization
- runnable Examples for lagoon, attach, compass, surf, wire, bouncer,
  wristband, postcard, phrasebook and festival; lagoon TestDocs* regions
  run on the package's Postgres harness through DocsDB
- 15 new required pages

modules/lagoon/export_docs_test.go

@@ -0,0 +1,21 @@
+package lagoon
+
+import (
+	"testing"
+
+	"gorm.io/gorm"
+)
+
+// DocsDB returns a GORM handle on a fresh ICU pl-PL database named name in
+// this package's Postgres harness, for the database-backed docs examples in
+// example_test.go. It skips under -short and fails when the harness has no
+// database, like the package's other database tests.
+func DocsDB(t *testing.T, name string) *gorm.DB {
+	t.Helper()
+	db, _ := dedicatedDB(t, name)
+	gdb, err := Use(t.Context(), db)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return gdb
+}