fix: playlist cover art, compilation tag, and year

- ripPlaylist/ripTrackCollection: pre-fetch playlist artwork once, embed in all tracks
- ripTrack: skip per-track album cover when playlist embed is provided
- buildTagMetadata: set COMPILATION=1 and year from playlist publish_date
- beatport: normalize playlistMetadata to include date fields for year extraction
- qobuz: normalize playlist image_rectangle to standard image map

internal/provider/qobuz/client.go

@@ -613,11 +613,13 @@ func (c *Client) getPlaylist(ctx context.Context, playlistID string) (map[string
 
 	total, _ := intValue(resp["tracks_count"])
 	if total <= pageLimit {
+		normalizePlaylistImage(resp)
 		return resp, nil
 	}
 
 	tracksObj, ok := mapValue(resp["tracks"])
 	if !ok {
+		normalizePlaylistImage(resp)
 		return resp, nil
 	}
 	items, ok := tracksObj["items"].([]any)
@@ -653,9 +655,25 @@ func (c *Client) getPlaylist(ctx context.Context, playlistID string) (map[string
 
 	tracksObj["items"] = items
 	resp["tracks"] = tracksObj
+	normalizePlaylistImage(resp)
 	return resp, nil
 }
 
+func normalizePlaylistImage(resp map[string]any) {
+	if resp["image"] != nil {
+		return
+	}
+	rect, ok := resp["image_rectangle"].([]any)
+	if !ok || len(rect) == 0 {
+		return
+	}
+	url, ok := rect[0].(string)
+	if !ok || url == "" {
+		return
+	}
+	resp["image"] = map[string]any{"original": url, "large": url}
+}
+
 func (c *Client) getLabel(ctx context.Context, labelID string) (map[string]any, error) {
 	pageLimit := 500
 	params := url.Values{}