feat: 增强文档转换失败处理机制

- 新增 FixStuckDocuments 命令用于修复卡住的文档
- 支持批量检测和修复超时的转换任务
- 改进重试按钮，支持 failed/processing/pending 状态
- 在确认对话框中显示当前状态和错误信息
- 提供 dry-run 模式预览修复操作

app/Filament/Resources/DocumentResource.php

@@ -226,12 +226,20 @@ class DocumentResource extends Resource
                     ->label('重试转换')
                     ->icon('heroicon-o-arrow-path')
                     ->color('warning')
-                    ->visible(fn (Document $record): bool => $record->conversion_status === 'failed')
+                    ->visible(fn (Document $record): bool => 
+                        in_array($record->conversion_status, ['failed', 'processing', 'pending'])
+                    )
                     ->requiresConfirmation()
                     ->modalHeading('重试文档转换')
                     ->modalDescription(fn (Document $record): string => 
                         '确定要重新转换文档 "' . $record->title . '" 吗？' . 
-                        ($record->conversion_error ? "\n\n上次失败原因：" . $record->conversion_error : '')
+                        "\n\n当前状态：" . match($record->conversion_status) {
+                            'failed' => '转换失败',
+                            'processing' => '转换中（可能卡住）',
+                            'pending' => '等待转换',
+                            default => $record->conversion_status,
+                        } .
+                        ($record->conversion_error ? "\n\n错误信息：" . $record->conversion_error : '')
                     )
                     ->modalSubmitActionLabel('确认重试')
                     ->action(function (Document $record) {