Open a TaskStream board when a project is created through the API

`taskstream: true` on POST /v1/projects also creates the project in
TaskStream, public, as the caller (their Pireon token is passed on), and
the answer carries `taskstream_key` and `taskstream_url`. The key is
`taskstream_key` or one made from the default-language slug.

The board is opened before the project is saved: if TaskStream refuses
it, nothing is created here and the reason comes back as a validation
error (502 when TaskStream does not answer). Machine tokens need the
server's own TASKSTREAM_TOKEN. Updates ignore the flag, and duplicates do
not inherit the link.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/Providers/AppServiceProvider.php

@@ -13,6 +13,7 @@ use App\Models\User;
 use App\Services\Git\GitManager;
 use App\Services\Pireon\PireonClient;
 use App\Services\Pireon\TokenStore;
+use App\Services\TaskStream\TaskStreamClient;
 use App\Support\Audit\Auditor;
 use App\Support\Webhooks\Webhooks;
 use Illuminate\Auth\Events\Login;
@@ -43,6 +44,8 @@ class AppServiceProvider extends ServiceProvider
 
         // Resolves git hosting drivers; see config/git.php.
         $this->app->singleton(GitManager::class);
+
+        $this->app->singleton(TaskStreamClient::class, fn () => TaskStreamClient::fromConfig(config('services.taskstream')));
     }
 
     /**