feat: add PHP limit overrides and runtime extension checks

- BackupEngine: set_time_limit(0), memory_limit 512M, ignore_user_abort,
  flush output buffers, disable zlib compression
- RestoreEngine: same PHP limit overrides
- FtpUploader: check ext-ftp before upload attempt
- GoogleDriveUploader: check ext-curl before upload attempt
- BackupEngine: check ext-zip and ext-mbstring at startup
- Kickstart restore.php: check ext-pdo_mysql and ext-mbstring in preflight,
  show max_execution_time and memory_limit in check results

Authored-by: Moko Consulting
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/packages/com_mokobackup/src/Engine/BackupEngine.php

@@ -30,6 +30,16 @@ class BackupEngine
 	 */
 	public function run(int $profileId, string $description, string $origin = 'backend'): array
 	{
+		// Override PHP limits for long-running backup operations
+		$this->overridePhpLimits();
+
+		// Verify required extensions
+		$extCheck = $this->checkRequiredExtensions();
+
+		if ($extCheck !== true) {
+			return ['success' => false, 'message' => $extCheck];
+		}
+
 		$db = Factory::getDbo();
 
 		// Load profile
@@ -221,6 +231,81 @@ class BackupEngine
 		}
 	}
 
+	/**
+	 * Override PHP execution limits for backup operations.
+	 * Attempts multiple methods since some hosts restrict ini_set.
+	 */
+	private function overridePhpLimits(): void
+	{
+		// Remove execution time limit (0 = unlimited)
+		@set_time_limit(0);
+		@ini_set('max_execution_time', '0');
+
+		// Increase memory limit for large sites
+		$currentMemory = $this->parseBytes(ini_get('memory_limit'));
+
+		if ($currentMemory > 0 && $currentMemory < 512 * 1024 * 1024) {
+			@ini_set('memory_limit', '512M');
+		}
+
+		// Disable output buffering to prevent memory buildup
+		while (@ob_end_clean()) {
+			// flush all output buffers
+		}
+
+		// Prevent browser/proxy timeout by disabling compression
+		@ini_set('zlib.output_compression', 'Off');
+
+		// Ignore user abort so backup completes even if browser closes
+		@ignore_user_abort(true);
+	}
+
+	/**
+	 * Parse a PHP ini byte value (e.g. "128M") into bytes.
+	 */
+	private function parseBytes(string $value): int
+	{
+		$value = trim($value);
+
+		if ($value === '-1' || $value === '') {
+			return -1;
+		}
+
+		$unit = strtolower(substr($value, -1));
+		$num  = (int) $value;
+
+		return match ($unit) {
+			'g' => $num * 1024 * 1024 * 1024,
+			'm' => $num * 1024 * 1024,
+			'k' => $num * 1024,
+			default => $num,
+		};
+	}
+
+	/**
+	 * Verify required PHP extensions are loaded.
+	 *
+	 * @return  true|string  True if all ok, or error message string
+	 */
+	private function checkRequiredExtensions(): true|string
+	{
+		$missing = [];
+
+		if (!extension_loaded('zip')) {
+			$missing[] = 'ext-zip (required for archive creation)';
+		}
+
+		if (!extension_loaded('mbstring') && !function_exists('mb_strlen')) {
+			$missing[] = 'ext-mbstring (required for binary-safe operations)';
+		}
+
+		if (!empty($missing)) {
+			return 'Missing PHP extensions: ' . implode(', ', $missing);
+		}
+
+		return true;
+	}
+
 	/**
 	 * Create the appropriate remote uploader based on the storage type.
 	 */

src/packages/com_mokobackup/src/Engine/FtpUploader.php

@@ -35,6 +35,10 @@ class FtpUploader implements RemoteUploaderInterface
 
 	public function upload(string $localPath, string $remoteName): array
 	{
+		if (!extension_loaded('ftp')) {
+			return ['success' => false, 'message' => 'PHP ext-ftp is required for FTP uploads. Enable it in php.ini.'];
+		}
+
 		if (empty($this->host)) {
 			return ['success' => false, 'message' => 'FTP host is not configured'];
 		}

src/packages/com_mokobackup/src/Engine/GoogleDriveUploader.php

@@ -37,6 +37,10 @@ class GoogleDriveUploader implements RemoteUploaderInterface
 
 	public function upload(string $localPath, string $remoteName): array
 	{
+		if (!extension_loaded('curl')) {
+			return ['success' => false, 'message' => 'PHP ext-curl is required for Google Drive uploads. Enable it in php.ini.'];
+		}
+
 		if (empty($this->clientId) || empty($this->refreshToken)) {
 			return ['success' => false, 'message' => 'Google Drive credentials not configured'];
 		}

src/packages/com_mokobackup/src/Engine/Kickstart.php

@@ -111,11 +111,21 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['action'])) {
     try {
         switch ($action) {
             case 'preflight':
+                // Override PHP limits for restore
+                @set_time_limit(0);
+                @ini_set('max_execution_time', '0');
+                @ini_set('memory_limit', '512M');
+                @ignore_user_abort(true);
+
                 $checks = [];
                 $checks['php_version'] = ['value' => PHP_VERSION, 'ok' => version_compare(PHP_VERSION, '8.1', '>=')];
                 $checks['zip_ext'] = ['value' => extension_loaded('zip') ? 'Yes' : 'No', 'ok' => extension_loaded('zip')];
+                $checks['pdo_mysql'] = ['value' => extension_loaded('pdo_mysql') ? 'Yes' : 'No', 'ok' => extension_loaded('pdo_mysql')];
+                $checks['mbstring'] = ['value' => extension_loaded('mbstring') ? 'Yes' : 'No', 'ok' => extension_loaded('mbstring')];
                 $checks['backup_exists'] = ['value' => file_exists(BACKUP_FILE) ? 'Yes' : 'No', 'ok' => file_exists(BACKUP_FILE)];
                 $checks['writable'] = ['value' => is_writable(RESTORE_DIR) ? 'Yes' : 'No', 'ok' => is_writable(RESTORE_DIR)];
+                $checks['max_execution_time'] = ['value' => ini_get('max_execution_time') ?: 'unlimited', 'ok' => true];
+                $checks['memory_limit'] = ['value' => ini_get('memory_limit'), 'ok' => true];
 
                 if (file_exists(BACKUP_FILE)) {
                     $checks['backup_size'] = ['value' => number_format(filesize(BACKUP_FILE) / 1048576, 2) . ' MB', 'ok' => true];

src/packages/com_mokobackup/src/Engine/RestoreEngine.php

@@ -41,6 +41,16 @@ class RestoreEngine
 	 */
 	public function restore(int $recordId, bool $restoreFiles = true, bool $restoreDb = true, bool $preserveConfig = true): array
 	{
+		// Override PHP limits — restores can take a long time
+		@set_time_limit(0);
+		@ini_set('max_execution_time', '0');
+		@ini_set('memory_limit', '512M');
+		@ignore_user_abort(true);
+
+		if (!extension_loaded('zip')) {
+			return ['success' => false, 'message' => 'PHP ext-zip is required for restore operations'];
+		}
+
 		$db = Factory::getDbo();
 
 		// Load backup record