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/services/card_service.py

@@ -579,6 +579,16 @@ class CardService:
         """Reactivate a deactivated loyalty card."""
         card = self.require_card(db, card_id)
         card.is_active = True
+
+        # Create reactivation transaction for audit trail
+        transaction = LoyaltyTransaction(
+            merchant_id=card.merchant_id,
+            card_id=card.id,
+            transaction_type=TransactionType.CARD_REACTIVATED.value,
+            transaction_at=datetime.now(UTC),
+        )
+        db.add(transaction)
+
         db.commit()
         db.refresh(card)