feat(#49): return FK details in department and municipality serializers

- DepartmentSerializer adds country_detail (nested country object)
- MunicipalitySerializer adds department_detail and country_detail
- Writable FK id fields kept for create/update
- Move geography brief serializers to serializers/geography.py

tienda_ilusion/don_confiao/services/provenance.py

@@ -1,7 +1,9 @@
-from ..serializers.provenance import (
+from ..serializers.geography import (
     CountryBriefSerializer,
     DepartmentBriefSerializer,
     MunicipalityBriefSerializer,
+)
+from ..serializers.provenance import (
     OrganizationBriefSerializer,
     SupplierBriefSerializer,
 )