Realistic demo data for performance testing (#2361)

* Realistic demo data for performance testing

* Add note about performance testing

* Fix bugbot issues

* More realistic account values

app/models/demo/base_scenario.rb

@@ -0,0 +1,30 @@
+# Base class for demo scenario handlers - subclasses must implement generate_family_data!
+class Demo::BaseScenario
+  def initialize(generators)
+    @generators = generators
+  end
+
+  def generate!(families, **options)
+    setup(**options) if respond_to?(:setup, true)
+
+    families.each do |family|
+      ActiveRecord::Base.transaction do
+        generate_family_data!(family, **options)
+      end
+      puts "#{scenario_name} data created for #{family.name}"
+    end
+  end
+
+  private
+
+    def setup(**options)
+    end
+
+    def generate_family_data!(family, **options)
+      raise NotImplementedError, "Subclasses must implement generate_family_data!(family, **options)"
+    end
+
+    def scenario_name
+      self.class.name.split("::").last.downcase.gsub(/([a-z])([A-Z])/, '\1 \2')
+    end
+end