fix(pricemon): load i18n in _alerts partial and pass alerts to include

AlertsPartialView (htmx-polled every 30s from the dashboard) returned
500 because _alerts.html used {% trans %} without {% load i18n %}.
Added the load tag so the partial renders correctly.

The dashboard's inline {% include 'pricemon/_alerts.html' %} also
relied on an undefined 'alerts' context var (DashboardView sets
'active_alerts'), so the alerts panel rendered empty even when alerts
existed. Pass alerts=active_alerts explicitly via the include.

Add regression tests covering both the dashboard render with an alert
and the alerts partial endpoint.

tests/test_pricemon.py

@@ -3,7 +3,7 @@ from unittest.mock import patch
 import pytest
 from django.urls import reverse
 
-from pricemon.models import PriceWatcher
+from pricemon.models import PriceAlert, PriceWatcher
 
 
 @pytest.fixture
@@ -16,6 +16,16 @@ def watcher():
         )
 
 
+@pytest.fixture
+def alert(watcher):
+    return PriceAlert.objects.create(
+        watcher=watcher,
+        old_price='100.00',
+        new_price='80.00',
+        drop_pct='20.00',
+    )
+
+
 @pytest.mark.django_db
 class TestPriceMonitorToggle:
     def test_dashboard_shows_disable_action_for_enabled_watcher(self, client, watcher):
@@ -53,3 +63,23 @@ class TestPriceMonitorToggle:
         response = client.get(reverse('pricemon-toggle-enabled', args=[watcher.pk]))
 
         assert response.status_code == 405
+
+
+@pytest.mark.django_db
+class TestPriceMonitorAlertsPartial:
+    def test_dashboard_renders_with_active_alert(self, client, watcher, alert):
+        response = client.get(reverse('pricemon-dashboard'))
+
+        assert response.status_code == 200
+        body = response.content.decode()
+        assert 'alert-{}'.format(alert.pk) in body
+        assert 'Price Drop Alerts' in body
+
+    def test_alerts_partial_renders_i18n_tags(self, client, watcher, alert):
+        response = client.get(reverse('pricemon-alerts-partial'))
+
+        assert response.status_code == 200
+        body = response.content.decode()
+        assert 'alert-{}'.format(alert.pk) in body
+        assert 'View' in body and 'Dismiss' in body
+        assert reverse('pricemon-dismiss-alert', args=[alert.pk]) in body