feat(#49): add geolocation (latitude/longitude) to municipalities

- Municipality model with optional latitude/longitude decimal fields
- Municipality and brief serializers expose lat/lng (also in product_provenance of public/authenticated summaries for the Leaflet map)
- seed_geography endpoint reads lat/lng and updates existing municipalities on reseed (idempotent)
- TDD tests for model, serializers, summaries and seed

tienda_ilusion/don_confiao/migrations/0054_municipality_latitude_municipality_longitude.py

@@ -0,0 +1,23 @@
+# Generated by Django 5.0.6 on 2026-08-16 08:29
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('don_confiao', '0053_country_organization_department_municipality_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='municipality',
+            name='latitude',
+            field=models.DecimalField(blank=True, decimal_places=7, max_digits=10, null=True),
+        ),
+        migrations.AddField(
+            model_name='municipality',
+            name='longitude',
+            field=models.DecimalField(blank=True, decimal_places=7, max_digits=10, null=True),
+        ),
+    ]