Add country

The code must match the Debezium topic prefix. The code, timezone and currency can't be changed later — double-check before saving.

Active base from: Charges counts subscriptions with any charge on the day (billing_core default). Renewal attempts counts subscriptions with a renewal_attempted history on the day, for platforms that don't store failed charges (LILM, Tamaituk). Use it when the platform's app/models/subscription.rb overrides active_base_in_period.