Entity-org scaffold should pre-populate codegen knobs

The compass add entity_org scaffold (and/or the codegen entity template behind it) should emit a model that already carries the basic variability knobs, switched on with sensible defaults, rather than an empty skeleton. Authoring the first synthetic model (ores.synthetic.gmm_component.org) showed the failure mode: a model that parses fine but is missing header/section knobs the render path needs (e.g. #+coding_scheme:, #+image_id:, has_tenant_id, the uuid-primary-key flag, the Qt/eventing enable block, etc.) silently generates empty files (just the licence header) instead of erroring. The scaffold should pre-populate those knobs (commented or defaulted) so a new entity generates real code out of the box, and ideally codegen should warn when a required knob is absent instead of emitting an empty file.

A brand-new component's first entity is exactly when the author least knows the full knob set. Discovering the requirement only via empty output (no error, no warning) is a poor authoring experience and cost real debugging time. Shipping the knobs in the scaffold — and failing loud on missing ones — makes codegen self-documenting and prevents silent empty generation. Raised while regenerating the synthetic config types via codegen.

• ores.synthetic.gmm_component — the first synthetic model that hit this.
• ores.refdata.country — the reference model with the full knob set.
• projects/ores.codegen/library/templates/cpp_domain_type_class.hpp.mustache — body wrapped in {{#domain_entity}}; renders empty when context lacks it.
• projects/ores.codegen/src/codegen/org_loader.py — org_document_to_model.

• Task: Regenerate synthetic config types via codegen (backend) — blocked on this.

This is one of three friction points found onboarding the first synthetic entity; the full picture (component registration in component_catalogue.org, scaffold knobs, and the legacy renderer that silently empties new org models — which must NOT be used, it is being removed) is consolidated in the companion capture below. The simplification ask: one modern command that registers the component, scaffolds a knob-filled model, and generates via the modern renderer, failing loudly instead of writing empty files.

• Codegen CLI legacy renderer emits empty files for minimal org models — the consolidated onboarding-friction capture.