fix: Add CancellationToken to Slack.PostWebHookMessage and remove unused IHttpClientFactory (#1547, #1583) (#1691)

- Add CancellationToken parameter to ISlack.PostWebHookMessage interface
- Update Slack implementation to accept and check CancellationToken
- Remove unused IHttpClientFactory parameter from Http class constructor

Fixes #1547, #1583

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: thomhurst

src/ModularPipelines.Slack/ISlack.cs

@@ -4,5 +4,5 @@ namespace ModularPipelines.Slack;
 
 public interface ISlack
 {
-    Task PostWebHookMessage(SlackWebHookOptions options);
+    Task PostWebHookMessage(SlackWebHookOptions options, CancellationToken cancellationToken = default);
 }

src/ModularPipelines.Slack/Slack.cs

@@ -13,10 +13,12 @@ public Slack(IHttp http)
         _http = http;
     }
 
-    public async Task PostWebHookMessage(SlackWebHookOptions options)
+    public async Task PostWebHookMessage(SlackWebHookOptions options, CancellationToken cancellationToken = default)
     {
+        cancellationToken.ThrowIfCancellationRequested();
+
         var slackClient = new SlackClient(options.WebHookUri.AbsoluteUri, httpClient: _http.GetLoggingHttpClient());
 
         await slackClient.PostAsync(options.SlackMessage);
     }
-}
+}

src/ModularPipelines/Http/Http.cs

@@ -20,7 +20,6 @@ internal class Http : IHttp, IDisposable
 
     public Http(HttpClient defaultHttpClient,
         IModuleLoggerProvider moduleLoggerProvider,
-        IHttpClientFactory httpClientFactory,
         IHttpLogger httpLogger,
         IOptions<PipelineOptions> pipelineOptions)
     {