Fix unusable personal settings form: v8 Vue idioms and Deck relations

The settings page rendered, but nothing in it worked:

- All NcSelect dropdowns showed "undefined" for every option. In
  @nextcloud/vue 9 the `label` prop is vue-select's option display *key*,
  not a caption, so `label="Board"` read `option.Board`. Use `input-label`.
- Saving always failed with "Bitte einen Titel angeben". Vue 3 dropped
  `.sync`; NcTextField and NcCheckboxRadioSwitch bind via `modelValue`, so
  `:value.sync` / `:checked.sync` never wrote back. Use `v-model`.
- NcButton's style prop is now `variant`, `type` is the native button type
  and `native-type` is gone. `type="tertiary"` rendered
  `<button type="tertiary">`, which HTML falls back to `submit` for, making
  the cancel button submit the form.
- The user dropdown was always empty. Deck's RelationalEntity replaces
  resolved relations with a RelationalObject once an entity is enriched, so
  `$acl->getParticipant()` returns that wrapper and the uid lives in
  `getPrimaryKey()` -- probing for `getUID()` yielded null. This also broke
  the background job's assigned-user filter, which shares the extractor.
- A board's ACL never contains its owner (a private board has an empty
  ACL), so participants are now seeded with the owner, group ACL entries
  are expanded via IGroupManager and display names resolved via
  IUserManager.
- One board appeared twice: getUserBoards() merges own/group/circle boards
  and includes archived and trashed ones. Deduplicate by id and drop those.

Also keep one failing lookup in onBoardChange from taking the other two
dropdowns down with it, and document all of the above in CLAUDE.md.

lib/Service/DeckIntegrationService.php

@@ -10,7 +10,9 @@ use OCA\Deck\Service\BoardService;
 use OCA\Deck\Service\CardService;
 use OCA\Deck\Service\StackService;
 use OCP\App\IAppManager;
+use OCP\IGroupManager;
 use OCP\IUser;
+use OCP\IUserManager;
 use OCP\Server;
 use Psr\Log\LoggerInterface;
 use Throwable;
@@ -28,8 +30,18 @@ use Throwable;
 class DeckIntegrationService {
 	private const DECK_APP_ID = 'deck';
 
+	/**
+	 * Deck's Acl::PERMISSION_TYPE_* values, inlined so this class keeps
+	 * working (degrading to "treat it as a user") if Deck ever moves or
+	 * renames the constants.
+	 */
+	private const ACL_TYPE_USER = 0;
+	private const ACL_TYPE_GROUP = 1;
+
 	public function __construct(
 		private IAppManager $appManager,
+		private IUserManager $userManager,
+		private IGroupManager $groupManager,
 		private LoggerInterface $logger,
 	) {
 	}
@@ -51,10 +63,30 @@ class DeckIntegrationService {
 			return $this->resolve(BoardService::class)->getUserBoards();
 		}, []);
 
-		return array_map(
-			static fn ($board) => ['id' => $board->getId(), 'title' => $board->getTitle()],
-			$boards,
-		);
+		// Deck merges own/group/circle boards, so the same board can come
+		// back more than once; and boards in the trash or archived ones are
+		// no useful automation target. Keyed by id => deduplicated.
+		$result = [];
+		foreach ($boards as $board) {
+			$id = (int)$board->getId();
+			if (isset($result[$id]) || $this->isBoardHidden($board)) {
+				continue;
+			}
+			$title = $board->getTitle();
+			$result[$id] = [
+				'id' => $id,
+				'title' => (is_string($title) && $title !== '') ? $title : ('#' . $id),
+			];
+		}
+
+		return array_values($result);
+	}
+
+	private function isBoardHidden(mixed $board): bool {
+		if (method_exists($board, 'getDeletedAt') && (int)$board->getDeletedAt() > 0) {
+			return true;
+		}
+		return method_exists($board, 'getArchived') && $board->getArchived() === true;
 	}
 
 	/**
@@ -87,25 +119,65 @@ class DeckIntegrationService {
 	}
 
 	/**
+	 * Everyone who can hold a card on this board: the board owner (who is
+	 * *not* part of the ACL — a private board has an empty ACL) plus every
+	 * ACL entry, with group shares expanded to their members.
+	 *
 	 * @return array<int, array{uid: string, displayName: string}>
 	 */
 	public function listParticipants(int $boardId): array {
-		$acl = $this->call(function () use ($boardId) {
+		$uids = $this->call(function () use ($boardId) {
 			$board = $this->resolve(BoardService::class)->find($boardId, true);
-			return $board->getAcl() ?? [];
+
+			$uids = [];
+			$owner = $this->unwrapUid($board->getOwner());
+			if ($owner !== null) {
+				$uids[] = $owner;
+			}
+
+			foreach ($board->getAcl() ?? [] as $entry) {
+				$principal = $this->extractParticipantUid($entry);
+				if ($principal === null) {
+					continue;
+				}
+				$type = method_exists($entry, 'getType') ? (int)$entry->getType() : self::ACL_TYPE_USER;
+				if ($type === self::ACL_TYPE_GROUP) {
+					array_push($uids, ...$this->groupMemberUids($principal));
+				} elseif ($type === self::ACL_TYPE_USER) {
+					$uids[] = $principal;
+				}
+				// Circles and federated shares are skipped: their members
+				// cannot be resolved to plain uids here.
+			}
+
+			return $uids;
 		}, []);
 
 		$participants = [];
-		foreach ($acl as $entry) {
-			$uid = $this->extractParticipantUid($entry);
-			if ($uid !== null && !isset($participants[$uid])) {
-				$participants[$uid] = ['uid' => $uid, 'displayName' => $uid];
+		foreach ($uids as $uid) {
+			if (isset($participants[$uid])) {
+				continue;
 			}
+			$participants[$uid] = [
+				'uid' => $uid,
+				'displayName' => $this->userManager->get($uid)?->getDisplayName() ?? $uid,
+			];
 		}
 
 		return array_values($participants);
 	}
 
+	/**
+	 * @return string[]
+	 */
+	private function groupMemberUids(string $groupId): array {
+		$group = $this->groupManager->get($groupId);
+		if ($group === null) {
+			return [];
+		}
+		return array_map(static fn (IUser $user) => $user->getUID(), $group->getUsers());
+	}
+
 	/**
 	 * Cards in the given stack that are neither archived nor marked done,
 	 * enriched so getAssignedUsers()/getLabels() are populated.
@@ -208,20 +280,57 @@ class DeckIntegrationService {
 	 * on one fixed method signature.
 	 */
 	private function extractParticipantUid(mixed $entry): ?string {
-		if (is_string($entry)) {
-			return $entry;
+		$uid = $this->unwrapUid($entry);
+		if ($uid !== null) {
+			return $uid;
 		}
 		if (!is_object($entry)) {
 			return null;
 		}
 		foreach (['getParticipant', 'getUid', 'getParticipantUid', 'getUserId'] as $method) {
 			if (method_exists($entry, $method)) {
-				$value = $entry->$method();
-				if (is_string($value) && $value !== '') {
-					return $value;
+				$uid = $this->unwrapUid($entry->$method());
+				if ($uid !== null) {
+					return $uid;
 				}
-				if (is_object($value) && method_exists($value, 'getUID')) {
-					return $value->getUID();
+			}
+		}
+		return null;
+	}
+
+	/**
+	 * Turns whatever Deck hands out for a "participant"/"owner" field into
+	 * a plain uid.
+	 *
+	 * Enriched Deck entities do *not* return the raw uid string: their
+	 * RelationalEntity base swaps resolved relations for a
+	 * OCA\Deck\Db\RelationalObject wrapping a User/Group object, and its
+	 * primary key is the uid we want. Unenriched entities still return the
+	 * bare string, so both shapes are handled.
+	 */
+	private function unwrapUid(mixed $value): ?string {
+		if (is_string($value)) {
+			return $value !== '' ? $value : null;
+		}
+		if (!is_object($value)) {
+			return null;
+		}
+		foreach (['getPrimaryKey', 'getUID', 'getUid', 'getId'] as $method) {
+			if (method_exists($value, $method)) {
+				$inner = $value->$method();
+				if (is_string($inner) && $inner !== '') {
+					return $inner;
+				}
+			}
+		}
+		if (method_exists($value, 'getObject')) {
+			$inner = $value->getObject();
+			foreach (['getUID', 'getUid', 'getId'] as $method) {
+				if (is_object($inner) && method_exists($inner, $method)) {
+					$uid = $inner->$method();
+					if (is_string($uid) && $uid !== '') {
+						return $uid;
+					}
 				}
 			}
 		}