feat: Implement user permission checks and manual payment functionalities

- Added CheckUserPermissionQuery and CheckUserPermissionQueryHandler for permission validation.
- Introduced GetUserRolesQuery and GetUserRolesQueryHandler to retrieve user roles.
- Created IPermissionService interface and its implementation in PermissionService.
- Defined permission and role constants in PermissionDefinitions.
- Developed SetDefaultVatPercentageCommand and its handler for VAT configuration.
- Implemented GetCurrentVatPercentageQuery and handler to fetch current VAT settings.
- Added manual payment commands: CreateManualPayment, ApproveManualPayment, and RejectManualPayment with respective handlers and validators.
- Created GetManualPaymentsQuery and handler for retrieving manual payment records.
- Integrated gRPC services for manual payments with appropriate permission checks.
- Established Protobuf definitions for manual payment operations and metadata.

src/BackOffice.BFF.Application/ConfigurationCQ/Queries/GetCurrentVatPercentage/GetCurrentVatPercentageQuery.cs

@@ -0,0 +1,17 @@
+namespace BackOffice.BFF.Application.ConfigurationCQ.Queries.GetCurrentVatPercentage;
+
+public record GetCurrentVatPercentageQuery : IRequest<GetCurrentVatPercentageResponse>;
+
+public class GetCurrentVatPercentageResponse
+{
+    /// <summary>
+    /// درصد VAT فعلی (مثلاً 10 به معنای 10٪)
+    /// </summary>
+    public int VatPercentage { get; set; }
+
+    /// <summary>
+    /// آیا مقدار از تنظیمات خوانده شده (true) یا مقدار پیش‌فرض استفاده شده (false)
+    /// </summary>
+    public bool IsConfigured { get; set; }
+}
+

src/BackOffice.BFF.Application/ConfigurationCQ/Queries/GetCurrentVatPercentage/GetCurrentVatPercentageQueryHandler.cs

@@ -0,0 +1,70 @@
+using BackOffice.BFF.Application.Common.Interfaces;
+using BackOffice.BFF.Configuration.Protobuf;
+using MediatR;
+using Microsoft.Extensions.Logging;
+
+namespace BackOffice.BFF.Application.ConfigurationCQ.Queries.GetCurrentVatPercentage;
+
+public class GetCurrentVatPercentageQueryHandler : IRequestHandler<GetCurrentVatPercentageQuery, GetCurrentVatPercentageResponse>
+{
+    private const string VatConfigurationKey = "DefaultVatPercentage";
+    private readonly IApplicationContractContext _context;
+    private readonly ILogger<GetCurrentVatPercentageQueryHandler> _logger;
+
+    public GetCurrentVatPercentageQueryHandler(
+        IApplicationContractContext context,
+        ILogger<GetCurrentVatPercentageQueryHandler> logger)
+    {
+        _context = context;
+        _logger = logger;
+    }
+
+    public async Task<GetCurrentVatPercentageResponse> Handle(GetCurrentVatPercentageQuery request, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var grpcRequest = new GetConfigurationByKeyRequest
+            {
+                Key = VatConfigurationKey
+            };
+
+            var response = await _context.Configurations.GetConfigurationByKeyAsync(grpcRequest, cancellationToken: cancellationToken);
+
+            if (response == null || string.IsNullOrWhiteSpace(response.Value))
+            {
+                _logger.LogInformation("VAT configuration not found. Using default value 10%.");
+                return new GetCurrentVatPercentageResponse
+                {
+                    VatPercentage = 10,
+                    IsConfigured = false
+                };
+            }
+
+            if (!int.TryParse(response.Value, out var vat) || vat < 0)
+            {
+                _logger.LogWarning("Invalid VAT configuration value '{Value}'. Falling back to default 10%.", response.Value);
+                return new GetCurrentVatPercentageResponse
+                {
+                    VatPercentage = 10,
+                    IsConfigured = false
+                };
+            }
+
+            return new GetCurrentVatPercentageResponse
+            {
+                VatPercentage = vat,
+                IsConfigured = true
+            };
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error while reading VAT configuration. Falling back to default value 10%.");
+            return new GetCurrentVatPercentageResponse
+            {
+                VatPercentage = 10,
+                IsConfigured = false
+            };
+        }
+    }
+}
+