feat(media): repurpose GIFs as video and serve converted mp4 when available

- Classify .gif as EAssetType.Video via MimeTypes (moved image/gif to the Video registry)
- Add MediaRepository.GetConvertedData, served by the existing media/{id} endpoint
  when a converted file exists on disk (with a fallback + warning log if missing)
- Expose the converted MIME type on AssetPreviewDto/AlbumAssetPreviewDto
  so the frontend can detect video assets from a single MimeType field

Lactose/Repositories/AlbumRepository.cs

@@ -177,6 +177,7 @@ public class AlbumRepository(LactoseDbContext context) : IAlbumRepository {
                 ResolutionHeight = a.ResolutionHeight,
                 HasThumbnail     = a.ThumbnailPath != null && a.ThumbnailPath != "",
                 HasPreview       = a.PreviewPath != null && a.PreviewPath != "",
+                MimeType         = a.ConvertedMimeType != null && a.ConvertedMimeType != "" ? a.ConvertedMimeType : a.MimeType,
                 FileName         = accessLevel >= EAccessLevel.Curator ? a.OriginalFilename : null,
                 Visibility       = accessLevel >= EAccessLevel.Maintainer ? a.Visibility : null,
                 DeletedAt        = accessLevel >= EAccessLevel.Admin || a.UploadedBy == userId ? a.DeletedAt : null

Lactose/Repositories/AssetRepository.cs

@@ -317,7 +317,7 @@ public class AssetRepository(LactoseDbContext context, ILogger<AssetRepository>
             .Where(a => pageIds.Contains(a.Id))
             .Select(a => new AssetPreviewDto {
                 Id               = a.Id,
-                MimeType         = a.MimeType,
+                MimeType         = a.ConvertedMimeType != null && a.ConvertedMimeType != "" ? a.ConvertedMimeType : a.MimeType,
                 ResolutionWidth  = a.ResolutionWidth,
                 ResolutionHeight = a.ResolutionHeight,
                 HasThumbnail     = a.ThumbnailPath != null && a.ThumbnailPath != "",
@@ -459,7 +459,6 @@ public class AssetRepository(LactoseDbContext context, ILogger<AssetRepository>
         return new Butter.Dtos.Asset.AssetBrowseResultDto {
             Directories = dirs,
             Assets = assetDtos,
-            CurrentPath = currentPath,
             TotalAssetCount = totalAtLevel
         };
     }

Lactose/Repositories/IMediaRepository.cs

@@ -33,4 +33,13 @@ public interface IMediaRepository : IDisposable {
     /// <param name="accessLevel">The requesting user's access level.</param>
     /// <returns>A <see cref="MediaDto"/> containing the media data, or null if not found or unauthorized.</returns>
     public MediaDto? GetPreviewData(Guid id, Guid? userId, EAccessLevel accessLevel = EAccessLevel.User);
+
+    /// <summary>
+    /// Retrieves the converted media data (e.g. the mp4 for an animated GIF).
+    /// </summary>
+    /// <param name="id">The ID of the media.</param>
+    /// <param name="userId">The ID of the user requesting the media.</param>
+    /// <param name="accessLevel">The requesting user's access level.</param>
+    /// <returns>A <see cref="MediaDto"/> containing the converted media data, or null if the asset has no converted file or is not visible.</returns>
+    public MediaDto? GetConvertedData(Guid id, Guid? userId, EAccessLevel accessLevel = EAccessLevel.User);
 }

Lactose/Repositories/MediaRepository.cs

@@ -93,6 +93,20 @@ public class MediaRepository(LactoseDbContext context, IPersonRepository personR
         };
     }
 
+    /// <inheritdoc />
+    public MediaDto? GetConvertedData(Guid id, Guid? userId, EAccessLevel accessLevel = EAccessLevel.User) {
+        var media = GetVisibleAsset(id, userId, accessLevel);
+
+        if (media == null) return null;
+
+        if (string.IsNullOrEmpty(media.ConvertedPath) || string.IsNullOrEmpty(media.ConvertedMimeType)) return null;
+
+        return new MediaDto {
+            MimeType = media.ConvertedMimeType,
+            Path     = media.ConvertedPath
+        };
+    }
+
     /// <inheritdoc />
     public void Dispose() {
         context.Dispose();