feat(loyalty): production readiness round 2 — 12 security, integrity & correctness fixes

Security:
- Fix TOCTOU race conditions: move balance/limit checks after row lock in redeem_points, add_stamp, redeem_stamps
- Add PIN ownership verification to update/delete/unlock store routes
- Gate adjust_points endpoint to merchant_owner role only

Data integrity:
- Track total_points_voided in void_points
- Add order_reference idempotency guard in earn_points

Correctness:
- Fix LoyaltyProgramAlreadyExistsException to use merchant_id parameter
- Add StorefrontProgramResponse excluding wallet IDs from public API
- Add bounds (±100000) to PointsAdjustRequest.points_delta

Audit & config:
- Add CARD_REACTIVATED transaction type with audit record
- Improve admin audit logging with actor identity and old values
- Use merchant-specific PIN lockout settings with global fallback
- Guard MerchantLoyaltySettings creation with get_or_create pattern

Tests: 27 new tests (265 total) covering all 12 items — unit and integration.

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

app/modules/loyalty/exceptions.py

@@ -43,11 +43,11 @@ class LoyaltyProgramNotFoundException(ResourceNotFoundException):
 class LoyaltyProgramAlreadyExistsException(ConflictException):
     """Raised when store already has a loyalty program."""
 
-    def __init__(self, store_id: int):
+    def __init__(self, merchant_id: int):
         super().__init__(
-            message=f"Store {store_id} already has a loyalty program",
+            message=f"Merchant {merchant_id} already has a loyalty program",
             error_code="LOYALTY_PROGRAM_ALREADY_EXISTS",
-            details={"store_id": store_id},
+            details={"merchant_id": merchant_id},
         )