Add support for multiple images from Twitter links

- Fetch all images from Twitter syndication API (photos array)
- Store images with unified 'image' media type (first = thumbnail by ID order)
- Display multi-image tweets in grid layout on detail page
- Add hover cycling through images on home grid (2s interval)
- Show image count indicator on multi-image items
- Extract shared downloadAndStoreImages() helper for create/refresh
- Add migration to convert existing thumbnail/gallery types to image
- Make images clickable to open in new tab on detail page

internal/handlers/api_items.go

@@ -23,6 +23,7 @@ type itemResponse struct {
 	MediaID            *int64   `json:"mediaId,omitempty"`
 	ThumbnailID        *int64   `json:"thumbnailId,omitempty"`
 	ThumbnailSourceURL *string  `json:"thumbnailSourceUrl,omitempty"`
+	GalleryIDs         []int64  `json:"galleryIds,omitempty"` // Additional images (for multi-image tweets)
 }
 
 type createItemRequest struct {
@@ -251,16 +252,23 @@ func buildItemResponse(ctx context.Context, rc *RequestContext, it item.Row) (it
 	}
 
 	// Get media IDs
+	// Media is ordered by ID, so first "image" is the thumbnail, rest are gallery
 	mediaList, err := media.QFindByItemID(ctx, rc.DB, it.ID)
 	if err != nil {
 		return itemResponse{}, err
 	}
+	firstImage := true
 	for _, m := range mediaList {
 		if m.MediaType == "original" {
 			resp.MediaID = &m.ID
-		} else if m.MediaType == "thumbnail" {
-			resp.ThumbnailID = &m.ID
-			resp.ThumbnailSourceURL = m.SourceURL
+		} else if m.MediaType == "image" {
+			if firstImage {
+				resp.ThumbnailID = &m.ID
+				resp.ThumbnailSourceURL = m.SourceURL
+				firstImage = false
+			} else {
+				resp.GalleryIDs = append(resp.GalleryIDs, m.ID)
+			}
 		}
 	}