Update GetEbookRating API to return rating 0 when no rating exists

internal/handlers/ebook.go

@@ -346,8 +346,12 @@ func (h *Handler) GetEbookRating(c echo.Context) error {
 	})
 	if err != nil {
 		if err == pgx.ErrNoRows {
-			// If no rating found, return 404
+			// If no rating found, return rating 0
-			return c.JSON(http.StatusNotFound, map[string]string{"error": "rating not found"})
+			return c.JSON(http.StatusOK, map[string]interface{}{
+				"ebook_id": ebookIdStr,
+				"user_id":  userID,
+				"rating":   0,
+			})
 		}
 		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
 	}