Issues fixed:
1. Country field was disabled when API failed (length 0)
- Changed: disabled={countries.length <= 1} → disabled={countries.length === 1}
- Only disables in single-country mode now
2. State field was disabled when no preloaded states
- Changed: Falls back to text input instead of disabled SearchableSelect
- Allows manual state entry for countries without state list
3. /countries API required admin permission
- Added public /countries endpoint to CheckoutController
- Uses permission_callback __return_true for customer checkout access
- Returns countries, states, and default_country
274c3d35e1