Notify board members about moved cards according to their Deck setting

Replaces the yes/no notify_email flag with notify_mode:
- off:   no mail
- owner: only the board owner, as before (migrated from notify_email=1)
- board: everyone with access to the board, filtered by their own Deck
         "Notifications" setting for it (board:<id>:notify-due: off /
         assigned / all), mirroring Deck's NotificationHelper rules

Recipients are resolved via PermissionService::findUsers() (owner, ACL,
groups and circles expanded), AssignmentMapper::isUserAssigned() and
IConfig, none of which reads Deck's frozen $userId. If they cannot be
resolved, no mail is sent rather than one to the wrong people.

Moved cards are collected over the whole run and each recipient gets a
single digest mail afterwards, in their own language.

Bumps to 35.2.0 so the migrations run.

lib/Service/WorkflowRunner.php

@@ -38,6 +38,13 @@ class WorkflowRunner {
 
 	private ?IUser $impersonationRestore = null;
 
+	/**
+	 * Moved cards per recipient uid, collected over the whole run.
+	 *
+	 * @var array<string, list<array{workflow: Workflow, card: Card, targets: array{board: string, sourceStack: string, targetStack: string}}>>
+	 */
+	private array $pendingMails = [];
+
 	public function __construct(
 		private WorkflowMapper $workflowMapper,
 		private DeckIntegrationService $deckService,
@@ -56,6 +63,7 @@ class WorkflowRunner {
 			return;
 		}
 
+		$this->pendingMails = [];
 		$byUser = [];
 		$owners = [];
 		foreach ($workflows as $workflow) {
@@ -80,6 +88,8 @@ class WorkflowRunner {
 				]);
 			}
 		}
+
+		$this->sendPendingMails();
 	}
 
 	/**
@@ -211,10 +221,7 @@ class WorkflowRunner {
 			return;
 		}
 
-		// Resolved at most once per run, and only if a card actually moves
-		// and the workflow wants a mail — this is decoration, not a check.
-		$targets = null;
-
+		$moved = [];
 		$now = $this->timeFactory->getDateTime();
 
 		foreach ($cards as $card) {
@@ -230,22 +237,96 @@ class WorkflowRunner {
 				'target' => $workflow->getTargetStackId(),
 			]);
 
-			if (!$this->moveCard($workflow, $card)) {
-				continue;
-			}
-
-			if ($workflow->getNotifyEmail()) {
-				$targets ??= $this->deckService->describeTargets(
-					$workflow->getBoardId(),
-					$workflow->getSourceStackId(),
-					$workflow->getTargetStackId(),
-				);
-				$this->mailer->sendCardMovedNotification($user, $workflow, $card, $targets);
+			if ($this->moveCard($workflow, $card)) {
+				$moved[] = $card;
 			}
 		}
 
 		$workflow->setLastRun($this->timeFactory->getDateTime());
 		$this->workflowMapper->update($workflow);
+
+		if ($moved !== []) {
+			$this->queueMails($user, $workflow, $moved);
+		}
+	}
+
+	/**
+	 * Works out who hears about the moved cards and parks them in
+	 * $pendingMails; sendPendingMails() delivers them once per recipient at
+	 * the end of the run.
+	 *
+	 * Mails are decoration, not part of the move: nothing in here may fail
+	 * the workflow, and if Deck cannot say who wants a mail, nobody gets one
+	 * rather than people who asked Deck for silence.
+	 *
+	 * @param Card[] $cards
+	 */
+	private function queueMails(IUser $owner, Workflow $workflow, array $cards): void {
+		$cardIds = array_map(static fn (Card $card): int => (int)$card->getId(), $cards);
+
+		switch ($workflow->getNotifyMode()) {
+			case NotificationPolicy::MODE_OWNER:
+				$recipients = array_fill_keys($cardIds, [$owner->getUID()]);
+				break;
+			case NotificationPolicy::MODE_BOARD:
+				try {
+					$recipients = $this->deckService->findNotificationRecipients($workflow->getBoardId(), $cardIds);
+				} catch (DeckUnavailableException $e) {
+					$this->logger->warning('No mails for workflow {id}: ' . $e->getMessage(), [
+						'app' => 'workflow_deck_automation',
+						'id' => $workflow->getId(),
+					]);
+					return;
+				}
+				break;
+			default:
+				return;
+		}
+
+		$targets = $this->deckService->describeTargets(
+			$workflow->getBoardId(),
+			$workflow->getSourceStackId(),
+			$workflow->getTargetStackId(),
+		);
+
+		foreach ($cards as $card) {
+			foreach ($recipients[(int)$card->getId()] ?? [] as $uid) {
+				$this->pendingMails[$uid][] = [
+					'workflow' => $workflow,
+					'card' => $card,
+					'targets' => $targets,
+				];
+			}
+		}
+	}
+
+	/**
+	 * One mail per recipient and run, however many cards and workflows it
+	 * covers — a board with twenty overdue cards and fifteen members would
+	 * otherwise send three hundred mails at once.
+	 *
+	 * Runs after the per-user loop, so no impersonation is active any more.
+	 */
+	private function sendPendingMails(): void {
+		$pending = $this->pendingMails;
+		$this->pendingMails = [];
+
+		foreach ($pending as $uid => $entries) {
+			// Same reasoning as in run(): nothing may escape.
+			try {
+				$recipient = $this->userManager->get((string)$uid);
+				if ($recipient === null || !$recipient->isEnabled()) {
+					continue;
+				}
+				$this->mailer->sendCardsMovedNotification($recipient, $entries);
+			} catch (Throwable $e) {
+				$this->logger->error('Could not send the moved-cards mail to {user}: ' . $e->getMessage(), [
+					'app' => 'workflow_deck_automation',
+					'user' => $uid,
+					'exception' => $e,
+				]);
+			}
+		}
 	}
 
 	/**
@@ -289,7 +370,7 @@ class WorkflowRunner {
 			'target' => $brokenTarget,
 		]);
 
-		// Sent regardless of the workflow's notifyEmail setting: that flag is
+		// Sent to the owner regardless of the workflow's notifyMode: that is
 		// about moved cards, this is a one-off notice that the automation the
 		// user configured has been switched off. It stays one-off because a
 		// disabled workflow is not picked up again.