feat: add svg spinner

assets/loading.svg

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<svg
+  xmlns="http://www.w3.org/2000/svg"
+  xmlns:xlink="http://www.w3.org/1999/xlink"
+  width="34px"
+  height="34px"
+  viewBox="0 0 100 100"
+  preserveAspectRatio="xMidYMid"
+  style="display:block;animation-play-state:paused"
+>
+  <circle
+    class="bytm-loading-spinner"
+    cx="50"
+    cy="50"
+    fill="none"
+    stroke="#ffffff"
+    stroke-width="6"
+    r="25"
+    stroke-dasharray="117.80972450961724 41.269908169872416"
+    transform="matrix(1,0,0,1,0,0)"
+    style="animation-play-state:paused"
+  ></circle><!-- generated by https://loading.io/ -->
+</svg>