Switch the app to German as its only language

The app is used internally only and its settings page was German
already. Mails, controller error messages (shown in the form), the
settings section name and the mail sender are now written in German
directly instead of going through IL10N without any translation files.
Nextcloud's own mail footer is requested in German as well.

lib/Controller/WorkflowController.php

@@ -34,7 +34,7 @@ class WorkflowController extends OCSController {
 	private function currentUserId(): string {
 		$user = $this->userSession->getUser();
 		if ($user === null) {
-			throw new OCSPreconditionFailedException('Not logged in');
+			throw new OCSPreconditionFailedException('Nicht angemeldet');
 		}
 		return $user->getUID();
 	}
@@ -114,12 +114,12 @@ class WorkflowController extends OCSController {
 		try {
 			$workflow = $this->workflowMapper->findById($id);
 		} catch (DoesNotExistException $e) {
-			throw new OCSNotFoundException('Workflow not found');
+			throw new OCSNotFoundException('Workflow nicht gefunden');
 		}
 
 		if (!in_array($workflow->getBoardId(), $this->ownedBoardIds(), true)) {
 			// Same answer as for a missing id: don't reveal other users' workflows.
-			throw new OCSNotFoundException('Workflow not found');
+			throw new OCSNotFoundException('Workflow nicht gefunden');
 		}
 		return $workflow;
 	}
@@ -133,7 +133,7 @@ class WorkflowController extends OCSController {
 		try {
 			return $this->deckService->listOwnedBoards($userId);
 		} catch (DeckUnavailableException $e) {
-			throw new OCSPreconditionFailedException('Could not load your Deck boards: ' . $e->getMessage());
+			throw new OCSPreconditionFailedException('Deine Deck-Boards konnten nicht geladen werden: ' . $e->getMessage());
 		}
 	}
 
@@ -147,24 +147,24 @@ class WorkflowController extends OCSController {
 	private function assertDeck(): void {
 		$user = $this->userSession->getUser();
 		if ($user === null) {
-			throw new OCSPreconditionFailedException('Not logged in');
+			throw new OCSPreconditionFailedException('Nicht angemeldet');
 		}
 		try {
 			$this->deckService->assertDeckAvailable($user);
 		} catch (DeckUnavailableException $e) {
-			throw new OCSPreconditionFailedException('Deck is not available: ' . $e->getMessage());
+			throw new OCSPreconditionFailedException('Deck ist nicht verfügbar: ' . $e->getMessage());
 		}
 	}
 
 	private function validate(string $title, int $boardId, int $sourceStackId, int $targetStackId, string $notifyMode): void {
 		if (trim($title) === '') {
-			throw new OCSBadRequestException('Title must not be empty');
+			throw new OCSBadRequestException('Bitte einen Titel angeben.');
 		}
 		if ($sourceStackId === $targetStackId) {
-			throw new OCSBadRequestException('Source and target stack must differ');
+			throw new OCSBadRequestException('Quell- und Ziel-Stapel müssen sich unterscheiden.');
 		}
 		if (!NotificationPolicy::isValidMode($notifyMode)) {
-			throw new OCSBadRequestException('Notification mode must be one of: ' . implode(', ', NotificationPolicy::MODES));
+			throw new OCSBadRequestException('Ungültige E-Mail-Einstellung, erlaubt sind: ' . implode(', ', NotificationPolicy::MODES));
 		}
 
 		// Reject references to boards or stacks that are gone (or were never
@@ -184,7 +184,7 @@ class WorkflowController extends OCSController {
 			}
 		}
 		if ($board === null || $board['archived']) {
-			throw new OCSBadRequestException('The selected board does not exist, is archived or is not owned by you');
+			throw new OCSBadRequestException('Das gewählte Board existiert nicht, ist archiviert oder gehört dir nicht.');
 		}
 
 		$stackIds = array_map(
@@ -192,7 +192,7 @@ class WorkflowController extends OCSController {
 			$this->deckService->listStacks($boardId),
 		);
 		if (!in_array($sourceStackId, $stackIds, true) || !in_array($targetStackId, $stackIds, true)) {
-			throw new OCSBadRequestException('The selected stack does not exist on this board');
+			throw new OCSBadRequestException('Der gewählte Stapel existiert auf diesem Board nicht.');
 		}
 	}