The composite-groups PR (#3581) replaced the raw ent SubscriptionPlan
response of GET /admin/payment/plans with a projection struct but
dropped the currency field added by #4323. PlanEditDialog then read an
undefined currency, sent an empty string on save, and silently wiped
the stored plan currency. Restore currency plus created_at/updated_at
so the projection preserves the full original response shape.
shaw