Mirror the backend App\Enums\Media\Type on the frontend so "is this an
image/video/PDF?" has a single definition instead of being hand-written
(type === 'x' || mime_type startsWith ...) across a dozen files.
- add lib/mediaType.ts: MediaType union, classify(), fromMimeType(),
fromExtension(), isImage/isVideo/isDocument/isGif, acceptAttribute()
- route every MediaItem detection and every File-upload validator through it
- fix MediaDropzone rendering a typeless image item (AI/Unsplash/Giphy)
as a broken <video> via the img-vs-video v-else
- collapse getMediaIncompatibilityReason onto the shared
getMediaValidationWarning core (canSchedule / variant selection unchanged)
- tighten MediaItem/AssetMedia/SavedMedia/PickedMedia .type to MediaType
- replace GalleryBrowser's hardcoded accept list with acceptAttribute()
a8bed34d17