fix: Mark Modal-dependent household impact tests as integration

These tests hit the real Modal API endpoint and fail without
MODAL_TOKEN_ID/MODAL_TOKEN_SECRET configured.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: anth-volk

tests/test_analysis_household_impact.py

@@ -3,6 +3,8 @@
 from datetime import date
 from uuid import UUID, uuid4
 
+import pytest
+
 from policyengine_api.api.household_analysis import (
     UK_CONFIG,
     US_CONFIG,
@@ -314,6 +316,7 @@ def test_get_report_not_found(self, client):
 # ---------------------------------------------------------------------------
 
 
+@pytest.mark.integration
 class TestHouseholdImpactRecordCreation:
     """Tests for correct record creation."""
 
@@ -404,6 +407,7 @@ def test_report_links_simulations(self, client, session):
 # ---------------------------------------------------------------------------
 
 
+@pytest.mark.integration
 class TestHouseholdImpactDeduplication:
     """Tests for simulation/report deduplication."""
 
@@ -470,6 +474,7 @@ def test_different_policy_creates_different_simulation(self, client, session):
 # ---------------------------------------------------------------------------
 
 
+@pytest.mark.integration
 class TestGetHouseholdImpact:
     """Tests for GET /analysis/household-impact/{report_id}."""
 
@@ -500,6 +505,7 @@ def test_get_returns_report_data(self, client, session):
 # ---------------------------------------------------------------------------
 
 
+@pytest.mark.integration
 class TestUSHouseholdImpact:
     """Tests specific to US households."""