refactor(cards): series books JSON through the builder

GET /api/series/detail?name=… books array via BookCardsFromMediaItems.
Series had the third LibraryTypeMap call INSIDE its per-item loop —
ListLibraries ran once per book on the page; now once per request.

internal/handlers/series.go

@@ -3,7 +3,6 @@ package handlers
 import (
 	"bookhoard/internal/database"
 	"bookhoard/internal/services"
-	"bookhoard/internal/utils"
 	"context"
 	"net/http"
 	"strconv"
@@ -153,19 +152,7 @@ func (h *SeriesHandler) GetSeriesBooks(c *echo.Context) error {
 		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "Failed to load series books"})
 	}
 
-	bookCards := make([]BookInfo, 0, len(books))
+	bookCards := BookCardsFromMediaItems(books, LibraryTypeMap(c.Request().Context(), h.db))
-	for _, item := range books {
-		itemUUID, _ := uuid.FromBytes(item.ID.Bytes[0:16])
-		libTypes := LibraryTypeMap(c.Request().Context(), h.db)
-		bookCards = append(bookCards, BookInfo{
-			MediaItemID:    itemUUID.String(),
-			Title:          item.Title,
-			Author:         textToString(item.Author),
-			CoverImagePath: utils.ResolveMediaURL(item.LibraryID, item.CoverImagePath),
-			FormatGroup:    item.FormatGroup,
-			Badge:          MediaBadgeKind(item.FormatGroup, libTypes[uuid.UUID(item.LibraryID.Bytes).String()]),
-		})
-	}
 
 	return c.JSON(http.StatusOK, map[string]interface{}{
 		"name":       seriesName,