Let workflows move cards by start date instead of due date

Each workflow now has a trigger date (due or start): the runner compares
either the card's due date or its start date against now, read straight
from Deck's Card entity. Mails and Nextcloud notifications say whether
the card was overdue or reached its start date. Cards without the chosen
date stay put.

Deck only has a start date since 1.18 and Entity getters are magic, so
DeckIntegrationService::supportsStartdate() checks the property; without
it the form rejects start-date workflows and the runner skips them
without disabling them.

WorkflowRunner::isOverdue() becomes hasPassed(), as it now covers both
dates. Existing workflows keep the due date (migration Version1005).
Bumps to 35.4.0 so the migration runs.

lib/Migration/Version1005Date20261003120000.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\WorkflowDeckAutomation\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\DB\Types;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+/**
+ * Adds `trigger_date` (due / start, see TriggerDate::ALL): whether a card
+ * moves once its due date or once its start date is reached. Existing
+ * workflows get `due`, the only trigger there was, so nothing changes for
+ * them.
+ */
+class Version1005Date20261003120000 extends SimpleMigrationStep {
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+
+		if (!$schema->hasTable('wfda_workflows')) {
+			return null;
+		}
+
+		$table = $schema->getTable('wfda_workflows');
+		if ($table->hasColumn('trigger_date')) {
+			return null;
+		}
+
+		$table->addColumn('trigger_date', Types::STRING, [
+			'notnull' => true,
+			'length' => 16,
+			'default' => 'due',
+		]);
+
+		return $schema;
+	}
+}