feat(#49): add product provenance (suppliers, organizations, geography)

- Country, Department, Municipality models (municipality unique per department)
- Organization and Supplier models, Supplier links to organization and municipality
- Product.suppliers M2M to link products to one or more suppliers
- Authenticated CRUD APIs for organizations, suppliers, countries, departments and municipalities (write only for administrators)
- product_provenance domain data embedded in sale/catalog summaries (public and authenticated)
- seed_geography endpoint (admin, idempotent) and scripts/seed_geography.py using pycountry + DANE municipalities CSV
- TDD tests for models, API permissions/CRUD and summary provenance data

tienda_ilusion/don_confiao/services/provenance.py

@@ -0,0 +1,64 @@
+from ..serializers.provenance import (
+    CountryBriefSerializer,
+    DepartmentBriefSerializer,
+    MunicipalityBriefSerializer,
+    OrganizationBriefSerializer,
+    SupplierBriefSerializer,
+)
+from ..serializers.products import ListProductSerializer
+
+
+def build_product_provenance(products, request=None):
+    """Domain data for provenance charts.
+
+    Returns a list of products, each with its suppliers. Each supplier
+    entry includes the linked organization and the territorial hierarchy
+    (municipality -> department -> country) derived from the supplier's
+    municipality.
+    """
+    result = []
+    for product in products:
+        suppliers = []
+        supplier_qs = product.suppliers.all().select_related(
+            "organization", "municipality__department__country"
+        )
+        for supplier in supplier_qs:
+            municipality = supplier.municipality
+            entry = {
+                "supplier": SupplierBriefSerializer(supplier).data,
+                "organization": (
+                    OrganizationBriefSerializer(supplier.organization).data
+                    if supplier.organization
+                    else None
+                ),
+                "municipality": (
+                    MunicipalityBriefSerializer(municipality).data
+                    if municipality
+                    else None
+                ),
+                "department": (
+                    DepartmentBriefSerializer(
+                        municipality.department
+                    ).data
+                    if municipality
+                    else None
+                ),
+                "country": (
+                    CountryBriefSerializer(
+                        municipality.department.country
+                    ).data
+                    if municipality
+                    else None
+                ),
+            }
+            suppliers.append(entry)
+
+        result.append(
+            {
+                "product": ListProductSerializer(
+                    product, context={"request": request}
+                ).data,
+                "suppliers": suppliers,
+            }
+        )
+    return result