core: add jikan stale retry pipeline

internal/jikan/search.go

@@ -21,10 +21,17 @@ func (c *Client) Search(ctx context.Context, query string, page int) (SearchResu
 		return cached, nil
 	}
 
+	var stale SearchResult
+	hasStale := c.getStaleCache(ctx, cacheKey, &stale)
+
 	var result SearchResponse
 	reqURL := fmt.Sprintf("%s/anime?q=%s&limit=24&page=%d", c.baseURL, url.QueryEscape(query), page)
 
 	if err := c.fetchWithRetry(ctx, reqURL, &result); err != nil {
+		if hasStale {
+			return stale, nil
+		}
+
 		return SearchResult{}, err
 	}
 
@@ -47,10 +54,17 @@ func (c *Client) GetTopAnime(ctx context.Context, page int) (TopAnimeResult, err
 		return cached, nil
 	}
 
+	var stale TopAnimeResult
+	hasStale := c.getStaleCache(ctx, cacheKey, &stale)
+
 	var result TopAnimeResponse
 	reqURL := fmt.Sprintf("%s/top/anime?filter=bypopularity&limit=24&page=%d", c.baseURL, page)
 
 	if err := c.fetchWithRetry(ctx, reqURL, &result); err != nil {
+		if hasStale {
+			return stale, nil
+		}
+
 		return TopAnimeResult{}, err
 	}