Add Endpoints API integration tests

Added a new test class `EndpointsApiTests` to validate the `Endpoints` API functionality in the `ReC.Client`.
Tests include:
- Dependency injection resolution for the `Endpoints` API.
- Behavior of `CreateAsync` with minimal payload.
- Behavior of `UpdateAsync` with an unknown ID.
- Validation of `DeleteAsync` sending payload as query string.

Introduced necessary `using` directives and utilized the `CreateScopedClient` helper method for resource management.

tests/ReC.Tests/Client/EndpointsApiTests.cs

@@ -0,0 +1,91 @@
+using ReC.Application.Common.Procedures.UpdateProcedure.Dto;
+using ReC.Application.Endpoints.Commands;
+using ReC.Client;
+
+namespace ReC.Tests.Client;
+
+[TestFixture]
+public class EndpointsApiTests : RecClientTestBase
+{
+    [Test]
+    public void ReCClient_endpoints_api_is_resolvable_through_dependency_injection()
+    {
+        var (client, scope) = CreateScopedClient();
+        using var _ = scope;
+
+        Assert.That(client, Is.Not.Null);
+        Assert.That(client.Endpoints, Is.Not.Null);
+    }
+
+    [Test]
+    public void CreateAsync_with_minimal_payload_throws_or_completes()
+    {
+        var (client, scope) = CreateScopedClient();
+        using var _ = scope;
+
+        var payload = new InsertEndpointCommand
+        {
+            Active = true,
+            Description = "integration-test-endpoint",
+            Uri = "https://localhost/test"
+        };
+
+        try
+        {
+            client.Endpoints.CreateAsync(payload).GetAwaiter().GetResult();
+            Assert.Pass("Create completed.");
+        }
+        catch (ReCApiException ex)
+        {
+            Assert.That(ex.Method, Is.EqualTo("POST"));
+            Assert.That(ex.RequestUri!.AbsolutePath, Does.EndWith("api/Endpoints"));
+        }
+    }
+
+    [Test]
+    public void UpdateAsync_with_unknown_id_throws_or_completes()
+    {
+        var (client, scope) = CreateScopedClient();
+        using var _ = scope;
+
+        var payload = new UpdateEndpointDto
+        {
+            Active = false,
+            Description = "updated"
+        };
+
+        try
+        {
+            client.Endpoints.UpdateAsync(long.MaxValue, payload).GetAwaiter().GetResult();
+            Assert.Pass("Update completed.");
+        }
+        catch (ReCApiException ex)
+        {
+            Assert.That(ex.Method, Is.EqualTo("PUT"));
+        }
+    }
+
+    [Test]
+    public void DeleteAsync_sends_payload_as_query_string()
+    {
+        var (client, scope) = CreateScopedClient();
+        using var _ = scope;
+
+        var payload = new DeleteEndpointCommand
+        {
+            Start = long.MaxValue - 1,
+            End = long.MaxValue,
+            Force = false
+        };
+
+        try
+        {
+            client.Endpoints.DeleteAsync(payload).GetAwaiter().GetResult();
+        }
+        catch (ReCApiException ex)
+        {
+            Assert.That(ex.Method, Is.EqualTo("DELETE"));
+            Assert.That(ex.RequestUri!.Query, Does.Contain("Start=").And.Contains("End=").And.Contains("Force="));
+        }
+    }
+}