fix(latest): parse Kagane series cover IDs

backend/internal/latest/sites.go

@@ -165,16 +165,24 @@ var singleQuotedMetaAttrRe = regexp.MustCompile(`(?is)([a-z][a-z0-9:_-]*)\s*=\s*
 // the target detail entry avoids matching posters from recommended results.
 var comixInitialDataRe = regexp.MustCompile(`(?is)<script\b[^>]*\bid\s*=\s*["']initial-data["'][^>]*>(.*?)</script>`)
 
-// kagane's browser-fetched series response carries this published cover URL.
-// Decode the top-level field, not merely an image-shaped URL elsewhere in JSON.
+// kagane's browser-fetched series response publishes cover image IDs under
+// series_covers. The API's canonical compressed image route is the only URL
+// form accepted by the store and browser fetcher; no rendition is guessed.
 func kaganeCoverURL(body string) string {
 	var response struct {
-		Cover string `json:"cover"`
+		SeriesCovers []struct {
+			ImageID string `json:"image_id"`
+		} `json:"series_covers"`
 	}
 	if err := json.Unmarshal([]byte(body), &response); err != nil {
 		return ""
 	}
-	return publishedCoverURL(response.Cover)
+	for _, cover := range response.SeriesCovers {
+		if kaganeImageIDRe.MatchString(cover.ImageID) {
+			return "https://kagane.to/api/v2/image/" + cover.ImageID + "/compressed"
+		}
+	}
+	return ""
 }
 
 func comixCoverURL(seriesURL, body string) string {