fix: address PR review — remove dead code, consistent warnings key

- Remove dead checkRequiredExtensions() method (superseded by PreflightCheck)
- Add 'warnings' key to ALL return paths in BackupEngine::run() and
  SteppedBackupEngine::init() to prevent undefined key access on PHP 8.x
- Include preflight warnings in success, failure, and early-exit returns

source/packages/com_mokosuitebackup/src/Engine/BackupEngine.php

@@ -58,7 +58,7 @@ class BackupEngine
 		$profile = $db->loadObject();
 
 		if (!$profile) {
-			return ['success' => false, 'message' => 'Profile not found: ' . $profileId];
+			return ['success' => false, 'message' => 'Profile not found: ' . $profileId, 'warnings' => []];
 		}
 
 		// Log any preflight warnings
@@ -78,7 +78,7 @@ class BackupEngine
 		$this->backupDir = BackupDirectory::resolve($resolver->resolve($configuredDir));
 
 		if (!BackupDirectory::ensureReady($this->backupDir)) {
-			return ['success' => false, 'message' => 'Cannot create backup directory: ' . $this->backupDir, 'record_id' => 0];
+			return ['success' => false, 'message' => 'Cannot create backup directory: ' . $this->backupDir, 'record_id' => 0, 'warnings' => $preflightResult['warnings']];
 		}
 
 		// Create backup record
@@ -310,6 +310,7 @@ class BackupEngine
 				'success'   => true,
 				'message'   => 'Backup complete: ' . $archiveName . ' (' . $sizeHuman . ')',
 				'record_id' => $recordId,
+				'warnings'  => $preflightResult['warnings'],
 			];
 		} catch (\Throwable $e) {
 			$this->log('FATAL: ' . $e->getMessage());
@@ -338,7 +339,7 @@ class BackupEngine
 			// Dispatch event for actionlog and other listeners
 			$this->dispatchAfterRun(false, $recordId, $description, $profileId, $origin);
 
-			return ['success' => false, 'message' => 'Backup failed: ' . $e->getMessage(), 'record_id' => $recordId];
+			return ['success' => false, 'message' => 'Backup failed: ' . $e->getMessage(), 'record_id' => $recordId, 'warnings' => $preflightResult['warnings'] ?? []];
 		}
 	}
 
@@ -393,35 +394,6 @@ class BackupEngine
 		};
 	}
 
-	/**
-	 * Verify required PHP extensions are loaded.
-	 *
-	 * @return  true|string  True if all ok, or error message string
-	 */
-	private function checkRequiredExtensions(): true|string
-	{
-		$required = [
-			'zip'       => 'ext-zip (required for archive creation)',
-			'pdo'       => 'ext-pdo (required for database operations)',
-			'pdo_mysql' => 'ext-pdo_mysql (required for MySQL database dumps)',
-			'mbstring'  => 'ext-mbstring (required for binary-safe operations)',
-		];
-
-		$missing = [];
-
-		foreach ($required as $ext => $label) {
-			if (!extension_loaded($ext)) {
-				$missing[] = $label;
-			}
-		}
-
-		if (!empty($missing)) {
-			return 'Missing PHP extensions: ' . implode(', ', $missing);
-		}
-
-		return true;
-	}
-
 	/**
 	 * Create the appropriate archiver based on the archive format.
 	 */

source/packages/com_mokosuitebackup/src/Engine/SteppedBackupEngine.php

@@ -55,7 +55,7 @@ class SteppedBackupEngine
 		$profile = $db->loadObject();
 
 		if (!$profile) {
-			return ['error' => true, 'message' => 'Profile not found: ' . $profileId];
+			return ['error' => true, 'message' => 'Profile not found: ' . $profileId, 'warnings' => []];
 		}
 
 		// Create session