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_activities.py

@@ -0,0 +1,38 @@
+import pytest
+from fastapi import HTTPException
+
+from api.v1.modules.crm.activities import service
+from api.v1.modules.crm.activities.dto import ActivityCreate
+
+T, C = 1, 1
+
+
+def test_create_rejects_invalid_type(db):
+    with pytest.raises(HTTPException) as exc:
+        service.create_activity(db, ActivityCreate(activity_type="invalido", subject="x"), T, C)
+    assert exc.value.status_code == 422
+
+
+def test_complete_activity_sets_timestamp(db):
+    activity = service.create_activity(db, ActivityCreate(activity_type="call", subject="Llamar al cliente"), T, C)
+    assert activity.status == "pending"
+    done = service.complete_activity(db, activity.id, T, C)
+    assert done.status == "completed"
+    assert done.completed_at is not None
+
+
+def test_create_rejects_unknown_related_entity(db):
+    with pytest.raises(HTTPException) as exc:
+        service.create_activity(
+            db, ActivityCreate(activity_type="task", subject="x", opportunity_id=999), T, C
+        )
+    assert exc.value.status_code == 422
+
+
+def test_filter_by_type_and_status(db):
+    service.create_activity(db, ActivityCreate(activity_type="call", subject="a"), T, C)
+    service.create_activity(db, ActivityCreate(activity_type="meeting", subject="b"), T, C)
+    calls = service.get_activities(db, T, C, activity_type="call")
+    assert len(calls) == 1 and calls[0].activity_type == "call"
+    pending = service.get_activities(db, T, C, activity_status="pending")
+    assert len(pending) == 2