fix(cli): resolve CLI-008..013 — format validation, exit-code semantics, debug-stream cancellation/disposal, test coverage

src/ScadaLink.CLI/ManagementHttpClient.cs

@@ -9,8 +9,19 @@ public class ManagementHttpClient : IDisposable
     private readonly HttpClient _httpClient;
 
     public ManagementHttpClient(string baseUrl, string username, string password)
+        : this(new HttpClient(), baseUrl, username, password)
     {
-        _httpClient = new HttpClient { BaseAddress = new Uri(baseUrl.TrimEnd('/') + "/") };
+    }
+
+    /// <summary>
+    /// Test-only constructor that accepts a pre-built <see cref="HttpClient"/> (typically
+    /// over a stub <see cref="HttpMessageHandler"/>) so the request/response handling can
+    /// be exercised without a live server.
+    /// </summary>
+    internal ManagementHttpClient(HttpClient httpClient, string baseUrl, string username, string password)
+    {
+        _httpClient = httpClient;
+        _httpClient.BaseAddress = new Uri(baseUrl.TrimEnd('/') + "/");
         var credentials = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{username}:{password}"));
         _httpClient.DefaultRequestHeaders.Authorization =
             new AuthenticationHeaderValue("Basic", credentials);