Task: Bring country under codegen and verify zero-diff regeneration

Bring country under codegen: create ores.refdata.country.org following the currency model shape (the party_country junction model already exists), regenerate, and reconcile until regeneration is zero-diff against HEAD — or record explicitly why any part stays hand-written, as currency did for its C++ layer.

• ores.refdata.country.org exists and drives SQL generation.
• Regenerating country SQL is zero-diff against HEAD.
• Any layer deliberately left hand-written is recorded with rationale in the Result, mirroring currency's decision record.
• Depends on component regeneration working over org models (task on the org-migration story).

(Transient implementation strategy. Written when work starts; distilled into the parent story's * Decisions and cleared when the task closes. Plans do not outlive their task.)