Add TryResolveProfileIdAsync method for test profiles

Introduced the `TryResolveProfileIdAsync` method in the `RecApplicationTestBase` class to resolve a usable profile ID for tests. The method prioritizes a configured `FakeProfileId` and falls back to querying the database for the first available profile. Added necessary namespaces (`System.Linq`, `System.Threading.Tasks`, and `MediatR`) to support LINQ, async operations, and the `ISender` interface. Implemented dependency injection for querying profiles and added error handling to ensure robustness.

tests/ReC.Tests/Application/RecApplicationTestBase.cs

@@ -1,10 +1,14 @@
 using System;
 using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using MediatR;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using ReC.Application;
 using ReC.Application.Common.Options;
+using ReC.Application.Profile.Queries;
 using ReC.Infrastructure;
 
 namespace ReC.Tests.Application;
@@ -21,6 +25,31 @@ public abstract class RecApplicationTestBase : IDisposable
 
     protected IServiceProvider ServiceProvider { get; }
 
+    /// <summary>
+    /// Resolves a usable profile id for tests that require an existing profile in the database.
+    /// Prefers the configured <c>FakeProfileId</c> value; otherwise asks the server for the first
+    /// available profile via the standard read query. Returns <c>null</c> when no profile is
+    /// configured and none can be discovered.
+    /// </summary>
+    protected async Task<long?> TryResolveProfileIdAsync()
+    {
+        var configured = Configuration.GetValue<long?>("FakeProfileId");
+        if (configured is > 0)
+            return configured;
+
+        try
+        {
+            using var scope = ServiceProvider.CreateScope();
+            var sender = scope.ServiceProvider.GetRequiredService<ISender>();
+            var profiles = await sender.Send(new ReadProfileViewQuery { IncludeActions = false });
+            return profiles?.FirstOrDefault()?.Id;
+        }
+        catch
+        {
+            return null;
+        }
+    }
+
     private static IConfiguration BuildConfiguration()
     {
         var appSettingsPath = LocateApiAppSettings();