Merged PR 1990: feat(crm-data-access,checkout): improve primary bonus card selection logic

feat(crm-data-access,checkout): improve primary bonus card selection logic

Enhance getPrimaryBonusCard helper to sort cards alphabetically by code
when multiple primary cards exist or when no primary card is designated.
This ensures deterministic card selection across the application.

Add comprehensive test coverage for edge cases including:
- Multiple primary cards (returns first alphabetically)
- No primary cards (returns first alphabetically)
- Empty bonus cards array (returns undefined)

Add TODO comments in ShoppingCartService for future refactoring of
cart handling logic to improve code organization and reusability.

Ref: #5407

libs/checkout/data-access/src/lib/services/shopping-cart.service.ts

@@ -173,6 +173,7 @@ export class ShoppingCartService {
     return res.result as ShoppingCart;
   }
 
+  // TODO: Code Kommentieren + Beschreiben
   async completeRewardSelection({
     tabId,
     rewardSelectionItems,
@@ -222,6 +223,7 @@ export class ShoppingCartService {
     }
   }
 
+  // TODO: If Logik in eigene Funktionen auslagern - Für Remove die Update Funktion mit Quantity 0 nutzen, Code Kommentieren
   async #handleCart({
     shoppingCartId,
     itemId,
@@ -295,6 +297,7 @@ export class ShoppingCartService {
     }
   }
 
+  // TODO: If Logik in eigene Funktionen auslagern - Für Remove die Update Funktion mit Quantity 0 nutzen, Code Kommentieren
   async #handleRewardCart({
     rewardShoppingCartId,
     itemId,