feat(loyalty): Phase 2A — transactional email notifications

Add async email notifications for 5 loyalty lifecycle events, using
the existing messaging module infrastructure (EmailService, EmailLog,
store template overrides).

- New seed script: scripts/seed/seed_email_templates_loyalty.py
  Seeds 5 templates × 4 locales (en/fr/de/lb) = 20 rows. Idempotent.
  Renamed existing script to seed_email_templates_core.py.
- Celery task: loyalty.send_notification_email — async dispatch with
  3 retries and 60s backoff. Opens own DB session.
- Notification service: LoyaltyNotificationService with 5 methods
  that resolve customer/card/program into template variables and
  enqueue via Celery (never blocks request handlers).
- Enrollment: sends loyalty_enrollment + loyalty_welcome_bonus (if
  bonus > 0) after card creation commit.
- Stamps: sends loyalty_reward_ready when stamp target reached.
- Expiration task: sends loyalty_points_expiring 14 days before expiry
  (tracked via new last_expiration_warning_at column to prevent dupes),
  and loyalty_points_expired after points are zeroed.
- Migration loyalty_005: adds last_expiration_warning_at to cards.
- 8 new unit tests for notification service dispatch.
- Fix: rate limiter autouse fixture in integration tests to prevent
  state bleed between tests.

Templates: loyalty_enrollment, loyalty_welcome_bonus,
loyalty_points_expiring, loyalty_points_expired, loyalty_reward_ready.
All support store-level overrides via the existing email template UI.

Birthday + re-engagement emails deferred to future marketing module
(cross-platform: OMS, loyalty, hosting).

342 tests pass.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/loyalty/tests/integration/test_store_api.py

@@ -19,6 +19,16 @@ import pytest
 
 from app.modules.loyalty.models import LoyaltyCard, LoyaltyProgram, LoyaltyTransaction
 from app.modules.loyalty.models.loyalty_program import LoyaltyType
+
+
+@pytest.fixture(autouse=True)
+def _clear_rate_limiter():
+    """Reset the in-memory rate limiter before each test to prevent bleed."""
+    from middleware.decorators import rate_limiter
+
+    rate_limiter.clients.clear()
+    yield
+    rate_limiter.clients.clear()
 from app.modules.loyalty.models.loyalty_transaction import TransactionType
 from app.modules.tenancy.models import User
 
@@ -467,26 +477,30 @@ class TestStampEarnRedeem:
         self, client, stamp_store_headers, stamp_store_setup
     ):
         """POST /stamp returns 429 once the per-IP cap is exceeded."""
+        from unittest.mock import patch
+
         from middleware.decorators import rate_limiter
 
-        # Reset the in-memory limiter so prior tests don't bleed in
         rate_limiter.clients.clear()
 
         card = stamp_store_setup["card"]
-        # Cap is 60 per minute. Hit it 60 times and expect any 200/4xx but not
-        # a 429, then the 61st should be 429.
-        for _ in range(60):
-            client.post(
+        # Mock notification dispatch so 60 requests complete fast enough
+        # to stay within the rate limiter's 60-second window.
+        with patch(
+            "app.modules.loyalty.tasks.notifications.send_notification_email"
+        ):
+            for _ in range(60):
+                client.post(
+                    f"{BASE}/stamp",
+                    json={"card_id": card.id},
+                    headers=stamp_store_headers,
+                )
+
+            response = client.post(
                 f"{BASE}/stamp",
                 json={"card_id": card.id},
                 headers=stamp_store_headers,
             )
-
-        response = client.post(
-            f"{BASE}/stamp",
-            json={"card_id": card.id},
-            headers=stamp_store_headers,
-        )
         assert response.status_code == 429
 
         rate_limiter.clients.clear()