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>

public/openapi.yaml

@@ -1621,7 +1621,14 @@ paths:
     patch:
       tags: [Projects]
       summary: Update a project
-      description: Partial update. Translatable fields merge into the existing map.
+      description: |
+        Partial update. Translatable fields merge into the existing map.
+
+        `taskstream: true` opens a TaskStream board for a project that has none
+        yet, as on creation (`taskstream_key`, or one made from the slug); if
+        TaskStream refuses, the update is not saved either. A project that
+        already has a board keeps it, and `taskstream_key` without the flag is
+        ignored, so a client can PATCH back what it read.
       requestBody:
         required: true
         content:
@@ -5574,12 +5581,12 @@ components:
         demo_url: { type: string, format: uri, nullable: true }
         taskstream:
           type: boolean
-          description: On creation only. Also open a public board for it in TaskStream; see `POST /v1/projects`.
+          description: Also open a public board for it in TaskStream, on creation or when it has none yet; see `POST /v1/projects`.
         taskstream_key:
           type: string
           nullable: true
           pattern: "^[A-Za-z][A-Za-z0-9]{1,9}$"
-          description: On creation only, with `taskstream`. The key in TaskStream; made from the slug when left out.
+          description: Only read with `taskstream`. The key in TaskStream; made from the slug when left out.
         cover_image: { type: string, nullable: true, description: A path from `POST /v1/media` with `for=projects`. }
         started_at: { type: string, format: date, nullable: true }
         ended_at: { type: string, format: date, nullable: true }