feat(crm): dominio backend (cuentas, contactos, prospectos, embudos, oportunidades, actividades)

- Nuevo schema `crm` con 7 tablas multi-tenant (TenantScopedMixin + soft delete)
- Módulos FastAPI por dominio: models/dto/service/routes (patrón example)
- Métricas del dashboard (KPIs + embudo por etapa)
- Conversión de prospecto → cuenta/contacto/oportunidad (idempotente)
- Movimiento de oportunidad entre etapas (Kanban) con estado/probabilidad derivados
- 25 permisos registrados en PermissionRegistry
- Migración Alembic con upgrade/downgrade completos
- 24 tests de servicios (pytest) en verde

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/tests/test_contacts.py

@@ -0,0 +1,33 @@
+import pytest
+from fastapi import HTTPException
+
+from api.v1.modules.crm.accounts import service as accounts_service
+from api.v1.modules.crm.accounts.dto import AccountCreate
+from api.v1.modules.crm.contacts import service
+from api.v1.modules.crm.contacts.dto import ContactCreate
+
+T, C = 1, 1
+
+
+def test_create_contact_rejects_unknown_account(db):
+    with pytest.raises(HTTPException) as exc:
+        service.create_contact(db, ContactCreate(first_name="Juan", account_id=999), T, C)
+    assert exc.value.status_code == 422
+
+
+def test_create_and_list_by_account(db):
+    acc = accounts_service.create_account(db, AccountCreate(name="Empresa"), T, C)
+    contact = service.create_contact(
+        db,
+        ContactCreate(first_name="Ana", last_name="López", account_id=acc.id, is_primary=True),
+        T, C,
+    )
+    assert contact.account_id == acc.id
+    assert contact.is_primary is True
+    listed = service.get_contacts(db, T, C, account_id=acc.id)
+    assert len(listed) == 1 and listed[0].first_name == "Ana"
+
+
+def test_contact_without_account_is_allowed(db):
+    contact = service.create_contact(db, ContactCreate(first_name="Suelto"), T, C)
+    assert contact.account_id is None