[map] Disallow non-integer zoom levels

 map.js

@@ -1113,6 +1113,7 @@
                url: 'https://tiles.ttss.pl/x' + pixelRatio + '/{z}/{x}/{y}.png',
                maxZoom: 19,
                tilePixelRatio: pixelRatio,
                opaque: false,
            }),
        }),
        route_layer,
@@ -1132,6 +1133,7 @@
            center: ol.proj.fromLonLat([19.94, 50.06]),
            zoom: 14,
            maxZoom: 19,
            constrainResolution: true,
        }),
        controls: ol.control.defaults({
            attributionOptions: ({