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>

lib/Db/WorkflowMapper.php

@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\WorkflowDeckAutomation\Db;
+
+use OCP\AppFramework\Db\DoesNotExistException;
+use OCP\AppFramework\Db\MultipleObjectsReturnedException;
+use OCP\AppFramework\Db\QBMapper;
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\IDBConnection;
+
+/**
+ * @extends QBMapper<Workflow>
+ */
+class WorkflowMapper extends QBMapper {
+	public function __construct(IDBConnection $db) {
+		parent::__construct($db, 'wfda_workflows', Workflow::class);
+	}
+
+	/**
+	 * @throws DoesNotExistException
+	 * @throws MultipleObjectsReturnedException
+	 */
+	public function findForUser(int $id, string $userId): Workflow {
+		$qb = $this->db->getQueryBuilder();
+		$qb->select('*')
+			->from($this->getTableName())
+			->where($qb->expr()->eq('id', $qb->createNamedParameter($id, IQueryBuilder::PARAM_INT)))
+			->andWhere($qb->expr()->eq('user_id', $qb->createNamedParameter($userId)));
+
+		return $this->findEntity($qb);
+	}
+
+	/**
+	 * @return Workflow[]
+	 */
+	public function findAllForUser(string $userId): array {
+		$qb = $this->db->getQueryBuilder();
+		$qb->select('*')
+			->from($this->getTableName())
+			->where($qb->expr()->eq('user_id', $qb->createNamedParameter($userId)))
+			->orderBy('id', 'ASC');
+
+		return $this->findEntities($qb);
+	}
+
+	/**
+	 * @return Workflow[]
+	 */
+	public function findAllEnabled(): array {
+		$qb = $this->db->getQueryBuilder();
+		$qb->select('*')
+			->from($this->getTableName())
+			->where($qb->expr()->eq('enabled', $qb->createNamedParameter(true, IQueryBuilder::PARAM_BOOL)))
+			->orderBy('user_id', 'ASC')
+			->addOrderBy('id', 'ASC');
+
+		return $this->findEntities($qb);
+	}
+}