Refactor payment request handling to support role change top-ups

- Updated the `PaymentRequest` model to include a new `Kind` property, distinguishing between `Subscription` and `RoleChangeTopUp` requests.
- Modified the `TelegramNotifier` to accommodate the new request type, ensuring accurate notifications for role change top-ups.
- Enhanced the `ConfirmPaymentRequestCommandHandler` to handle role change top-ups without extending the billing period, reflecting the new payment logic.
- Updated various application components and tests to support the new payment request structure and ensure proper functionality.
- Revised API documentation to clarify the behavior of role change top-ups and their impact on billing.

backend/src/PnvPanel.Infrastructure/Persistence/Migrations/AppDbContextModelSnapshot.cs

@@ -293,11 +293,15 @@ namespace PnvPanel.Infrastructure.Persistence.Migrations
                     b.Property<Guid?>("DecidedBy")
                         .HasColumnType("uuid");
 
-                    b.Property<string>("Period")
+                    b.Property<string>("Kind")
                         .IsRequired()
                         .HasMaxLength(32)
                         .HasColumnType("character varying(32)");
 
+                    b.Property<string>("Period")
+                        .HasMaxLength(32)
+                        .HasColumnType("character varying(32)");
+
                     b.Property<string>("RejectionReason")
                         .HasMaxLength(500)
                         .HasColumnType("character varying(500)");