Open a TaskStream board for a project that has none yet

The project form gets «Crear en TaskStream» while the project has no
board, and `taskstream: true` on a PATCH does the same through the API.
A refusal leaves the edit unsaved; a project with a board keeps it, and
`taskstream_key` without the flag is still ignored.

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

app/Http/Requests/Api/V1/ProjectRequest.php

@@ -20,8 +20,9 @@ use Illuminate\Validation\Validator;
  * Relations travel as ids and are replaced whole when sent: `technology_ids`,
  * `service_ids`, and `members` with each one's role on the project.
  *
- * `taskstream` (on creation only) opens a public board in TaskStream for the
- * project, keyed `taskstream_key` or one derived from the slug.
+ * `taskstream` opens a public board in TaskStream for the project, keyed
+ * `taskstream_key` or one derived from the slug; on an update, only when the
+ * project has none yet.
  */
 class ProjectRequest extends FormRequest
 {
@@ -78,10 +79,10 @@ class ProjectRequest extends FormRequest
             'members.*.id' => ['required', 'integer', 'distinct', Rule::exists('members', 'id')->whereNull('deleted_at')],
             'members.*.role' => ['nullable', 'string', 'max:120'],
 
-            // Only when creating; a client PATCHing back what it read sends
-            // the key it got, which is ignored rather than refused.
-            'taskstream' => [$creating ? 'sometimes' : 'exclude', 'boolean'],
-            'taskstream_key' => [$creating ? 'sometimes' : 'exclude', 'nullable', 'string', 'regex:/^[A-Za-z][A-Za-z0-9]{1,9}$/'],
+            // The key is only read along with `taskstream`: a client PATCHing
+            // back what it read sends the key it got, which changes nothing.
+            'taskstream' => ['sometimes', 'boolean'],
+            'taskstream_key' => ['sometimes', 'nullable', 'string', 'regex:/^[A-Za-z][A-Za-z0-9]{1,9}$/'],
         ];
     }