Function getMimeType

src/renderer/src/hooks/useAttachment.ts:9–19

(fileName: string)

// 从文件名推断 MIME 类型
function getMimeType(fileName: string): string {
  const ext = fileName.split('.').pop()?.toLowerCase()
  const mimeMap: Record<string, string> = {
    jpg: 'image/jpeg',
    jpeg: 'image/jpeg',
    png: 'image/png',
    gif: 'image/gif',
    webp: 'image/webp'
  }
  return mimeMap[ext || ''] || 'image/jpeg'
}

// 生成唯一 ID
function generateId(): string {