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/Support/Duplicator.php

@@ -32,10 +32,12 @@ final class Duplicator
     ];
 
     /**
-     * Never copied: where it stands rather than what it says.
+     * Never copied: where it stands rather than what it says — and the
+     * TaskStream board, which belongs to the original alone.
      */
     protected const RESET = [
         'published_at', 'unpublish_at', 'review_requested_at', 'review_requested_by', 'reviewer_id',
+        'taskstream_project_id', 'taskstream_key',
     ];
 
     public static function supports(Model $record): bool