simplify Divide component to only set total on mousedown on divider

src/renderer/components/2-molecules/Divide.svelte

@@ -30,21 +30,14 @@ $: style = s({
   '--divide-min-height': minSize > 0 && mode === 'v' ? `${minSize}px` : '0',
 });
 
-onMount(() => {
-  total = getTotal();
-});
-
 function getTotal() {
   return mode === 'h' ? divide.clientWidth : divide.clientHeight;
 }
 
-function handleResize() {
-  total = getTotal();
-}
-
 function handleMousedown(event) {
   if (event.button === 0) {
     dragging = true;
+    total = getTotal();
   }
 }
 
@@ -121,8 +114,6 @@ function handleMouseenter(event) {
 }
 </style>
 
-<svelte:window on:resize="{handleResize}" />
-
 <div
   class="{classes}"
   {style}