feat: migrate ESLint to v9 flat config

- Replace .eslintrc.json with eslint.config.mjs
- Simplify configuration using @antfu/eslint-config
- Add necessary ESLint plugin dependencies
- Disable overly strict style rules
- Set package.json type to module for ESM support
- Fix ESLint disable comment format

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/components/base/file-uploader-in-attachment/file-item.tsx

@@ -24,7 +24,7 @@ import cn from '@/utils/classnames'
 import ReplayLine from '@/app/components/base/icons/other/ReplayLine'
 import ImagePreview from '@/app/components/base/image-uploader/image-preview'
 
-type FileInAttachmentItemProps = {
+interface FileInAttachmentItemProps {
   file: FileEntity
   showDeleteAction?: boolean
   showDownloadAction?: boolean