fix(user_status): add debug logging to silent failure paths

Multiple code paths in StatusService silently swallowed failures,
making it impossible to debug status reliability issues. Add debug
logging for: backup creation conflicts, aborted automated status
changes, failed revert operations, and concurrent insert conflicts.

AI-Assisted-By: Claude Opus 4.6
Signed-off-by: Anna Larch <anna@nextcloud.com>

Author: miaulalala

apps/user_status/lib/Service/StatusService.php

@@ -284,6 +284,7 @@ public function setUserStatus(string $userId,
 
 		if ($createBackup) {
 			if ($this->backupCurrentStatus($userId) === false) {
+				$this->logger->debug('Automated status change aborted for user ' . $userId . ': backup already exists (another automated status is active)', ['app' => 'user_status']);
 				return null; // Already a status set automatically => abort.
 			}
 
@@ -516,6 +517,7 @@ public function backupCurrentStatus(string $userId): bool {
 			return true;
 		} catch (Exception $ex) {
 			if ($ex->getReason() === Exception::REASON_UNIQUE_CONSTRAINT_VIOLATION) {
+				$this->logger->debug('Backup status already exists for user ' . $userId . ', skipping backup creation', ['app' => 'user_status']);
 				return false;
 			}
 			throw $ex;
@@ -533,7 +535,7 @@ public function revertUserStatus(string $userId, string $messageId, bool $revert
 
 		$deleted = $this->mapper->deleteCurrentStatusToRestoreBackup($userId, $messageId);
 		if (!$deleted) {
-			// Another status is set automatically or no status, do nothing
+			$this->logger->debug('Status revert skipped for user ' . $userId . ': current status does not match messageId "' . $messageId . '" (user may have changed status manually)', ['app' => 'user_status']);
 			return null;
 		}
 
@@ -589,10 +591,10 @@ protected function insertWithoutThrowingUniqueConstrain(UserStatus $userStatus):
 		try {
 			return $this->mapper->insert($userStatus);
 		} catch (Exception $e) {
-			// Ignore if a parallel request already set the status
 			if ($e->getReason() !== Exception::REASON_UNIQUE_CONSTRAINT_VIOLATION) {
 				throw $e;
 			}
+			$this->logger->debug('Concurrent insert conflict for user ' . $userStatus->getUserId() . ': status was already set by a parallel request', ['app' => 'user_status']);
 		}
 		return $userStatus;
 	}