Phase 7a: Cosmetic cleanup + delete orphaned PurchasePackage handler

- Delete orphaned PurchasePackageCommand handler (no RPC dispatch, no callers)
- Fix doc-comments: طلایی → پکیج in enums, entities, handlers
- Remove stale 56M inline comments
- Clean SystemConstants deprecated field docs

src/CMSMicroservice.Domain/Entities/User.cs

@@ -63,7 +63,7 @@ public class User : BaseAuditableEntity
     public DateTime? DayaCreditReceivedAt { get; set; }
     
     /// <summary>
-    /// نحوه خرید پکیج طلایی (برای جلوگیری از خرید مجدد)
+    /// نحوه خرید پکیج (برای جلوگیری از خرید مجدد)
     /// </summary>
     public PackagePurchaseMethod PackagePurchaseMethod { get; set; } = PackagePurchaseMethod.None;