refactor: Apply formatUtil code review feedback and improve type safety

- Remove deprecated getMediaKindFromFilename function (no usages found)
- Define MediaType using const assertion pattern
- Apply as const to extension arrays with type guards
- Use type assertions for type-safe includes checks

Author: viva-jinyi

packages/shared-frontend-utils/src/formatUtil.ts

@@ -475,11 +475,19 @@ export function formatDuration(milliseconds: number): string {
   return parts.join(' ')
 }
 
-// Module scope constants to avoid re-initialization on every call
-const IMAGE_EXTENSIONS = ['png', 'jpg', 'jpeg', 'gif', 'webp', 'bmp']
-const VIDEO_EXTENSIONS = ['mp4', 'webm', 'mov', 'avi']
-const AUDIO_EXTENSIONS = ['mp3', 'wav', 'ogg', 'flac']
-const THREE_D_EXTENSIONS = ['obj', 'fbx', 'gltf', 'glb']
+const IMAGE_EXTENSIONS = ['png', 'jpg', 'jpeg', 'gif', 'webp', 'bmp'] as const
+const VIDEO_EXTENSIONS = ['mp4', 'webm', 'mov', 'avi'] as const
+const AUDIO_EXTENSIONS = ['mp3', 'wav', 'ogg', 'flac'] as const
+const THREE_D_EXTENSIONS = ['obj', 'fbx', 'gltf', 'glb'] as const
+
+const MEDIA_TYPES = ['image', 'video', 'audio', '3D'] as const
+type MediaType = (typeof MEDIA_TYPES)[number]
+
+// Type guard helper for checking array membership
+type ImageExtension = (typeof IMAGE_EXTENSIONS)[number]
+type VideoExtension = (typeof VIDEO_EXTENSIONS)[number]
+type AudioExtension = (typeof AUDIO_EXTENSIONS)[number]
+type ThreeDExtension = (typeof THREE_D_EXTENSIONS)[number]
 
 /**
  * Truncates a filename while preserving the extension
@@ -518,28 +526,16 @@ export function truncateFilename(
  * @param filename The filename to analyze
  * @returns The media type: 'image', 'video', 'audio', or '3D'
  */
-export function getMediaTypeFromFilename(
-  filename: string
-): 'image' | 'video' | 'audio' | '3D' {
+export function getMediaTypeFromFilename(filename: string): MediaType {
   if (!filename) return 'image'
   const ext = filename.split('.').pop()?.toLowerCase()
   if (!ext) return 'image'
 
-  if (IMAGE_EXTENSIONS.includes(ext)) return 'image'
-  if (VIDEO_EXTENSIONS.includes(ext)) return 'video'
-  if (AUDIO_EXTENSIONS.includes(ext)) return 'audio'
-  if (THREE_D_EXTENSIONS.includes(ext)) return '3D'
+  // Type-safe array includes check using type assertion
+  if (IMAGE_EXTENSIONS.includes(ext as ImageExtension)) return 'image'
+  if (VIDEO_EXTENSIONS.includes(ext as VideoExtension)) return 'video'
+  if (AUDIO_EXTENSIONS.includes(ext as AudioExtension)) return 'audio'
+  if (THREE_D_EXTENSIONS.includes(ext as ThreeDExtension)) return '3D'
 
   return 'image'
 }
-
-/**
- * @deprecated Use getMediaTypeFromFilename instead - kept for backward compatibility
- * @param filename The filename to analyze
- * @returns The media kind: 'image', 'video', 'audio', or '3D'
- */
-export function getMediaKindFromFilename(
-  filename: string
-): 'image' | 'video' | 'audio' | '3D' {
-  return getMediaTypeFromFilename(filename)
-}