feat: wire Google Wallet into loyalty enrollment, stamps, and points flows

Connect the fully-implemented Google Wallet service to the loyalty module:
- Create wallet class/object on customer enrollment
- Sync wallet passes on stamp and points operations
- Expose wallet URLs in storefront API responses
- Add conditional "Add to Google Wallet" buttons on dashboard and enroll-success pages
- Use platform-wide env var config (not per-merchant DB column)
- Add Google service account patterns to .gitignore
- Add LOYALTY_GOOGLE_* fields to app Settings
- Update deployment docs and add local testing guide

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

app/modules/loyalty/services/card_service.py

@@ -416,6 +416,12 @@ class CardService:
         db.commit()
         db.refresh(card)
 
+        # Create wallet objects (Google Wallet, Apple Wallet)
+        # Lazy import to avoid circular imports; exception-safe (logs but doesn't raise)
+        from app.modules.loyalty.services.wallet_service import wallet_service
+
+        wallet_service.create_wallet_objects(db, card)
+
         logger.info(
             f"Enrolled customer {customer_id} in merchant {merchant_id} loyalty program "
             f"(card: {card.card_number}, bonus: {program.welcome_bonus_points} pts)"