Add Deck workflow automation Nextcloud app

Ports the standalone due-date cron script into a proper Nextcloud 34
app with a personal-settings UI, per-user workflow configuration
(source/target stack, assigned-user and label filters, email
notification), a TimedJob background runner, and Gitea CI pipelines.

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

appinfo/routes.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+return [
+	'ocs' => [
+		['name' => 'workflow#index', 'url' => '/api/v1/workflows', 'verb' => 'GET'],
+		['name' => 'workflow#create', 'url' => '/api/v1/workflows', 'verb' => 'POST'],
+		['name' => 'workflow#update', 'url' => '/api/v1/workflows/{id}', 'verb' => 'PUT'],
+		['name' => 'workflow#destroy', 'url' => '/api/v1/workflows/{id}', 'verb' => 'DELETE'],
+
+		['name' => 'workflow#boards', 'url' => '/api/v1/boards', 'verb' => 'GET'],
+		['name' => 'workflow#stacks', 'url' => '/api/v1/boards/{boardId}/stacks', 'verb' => 'GET'],
+		['name' => 'workflow#labels', 'url' => '/api/v1/boards/{boardId}/labels', 'verb' => 'GET'],
+		['name' => 'workflow#participants', 'url' => '/api/v1/boards/{boardId}/participants', 'verb' => 'GET'],
+	],
+];