fix: preserve plugin tool state.attachments in UI and materializer (#2367)

* preserve attachments in UI and materializer

* add support for non-image attachments

* preserve attachments in UI and materializer

* improve attachment rendering and state synchronization

* simplify attachment filtering and key handling

* prevent rendering tool attachments without URLs

* require `f.url` in `imageAttachments` to match gallery indices

packages/ui/src/lib/i18n/messages/ko.ts

@@ -2069,6 +2069,7 @@ export const dict: Record<I18nKey, string> = {
   'chat.toolPart.copiedOutput': '출력 복사됨',
   'chat.toolPart.copyOutputFailed': '출력을 복사하지 못했습니다',
   'chat.toolPart.openSubtask': '{type} 하위 작업 열기',
+  'chat.toolPart.attachmentFallback': '첨부 파일',
   'chat.todo.total': '전체',
   'chat.todo.inProgress': '진행 중',
   'chat.todo.pending': '대기 중',