Make the per-owner project cap configurable via env

Self-hosters shouldn't be stuck with a hardcoded 100-project limit;
MAX_PROJECTS_PER_OWNER now controls it, defaulting to 0 (unlimited).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/Http/Controllers/ProjectController.php

@@ -18,11 +18,12 @@ use Psr\Http\Message\ServerRequestInterface as Request;
 final class ProjectController extends ProjectScopedController
 {
     private const TITLE_MAX = 255;
-    private const MAX_PROJECTS_PER_OWNER = 100;
 
     public function __construct(
         ProjectRepository $projects,
         private readonly CardStatusRepository $statuses,
+        /** Maximum number of projects a single owner may create. 0 means unlimited. */
+        private readonly int $maxProjectsPerOwner,
     ) {
         parent::__construct($projects);
     }
@@ -48,9 +49,9 @@ final class ProjectController extends ProjectScopedController
         $title = $validator->requiredString('title', self::TITLE_MAX);
         $validator->assert();
 
-        if ($this->projects->countForOwner($ownerId) >= self::MAX_PROJECTS_PER_OWNER) {
+        if ($this->maxProjectsPerOwner > 0 && $this->projects->countForOwner($ownerId) >= $this->maxProjectsPerOwner) {
             throw new ApiException(
-                sprintf('You have reached the maximum of %d projects.', self::MAX_PROJECTS_PER_OWNER),
+                sprintf('You have reached the maximum of %d projects.', $this->maxProjectsPerOwner),
                 409,
             );
         }