fix(multiselect): Svelte 5 compatibility

Refactor the MultiSelect component to remove circular dependencies which
would cause infinite loops in Svelte 5 (#1986).

src/MultiSelect/MultiSelect.svelte

@@ -168,7 +168,7 @@
    */
   export let highlightedId = null;
 
-  import { afterUpdate, createEventDispatcher, setContext } from "svelte";
+  import { afterUpdate, createEventDispatcher, setContext, tick } from "svelte";
   import WarningFilled from "../icons/WarningFilled.svelte";
   import WarningAltFilled from "../icons/WarningAltFilled.svelte";
   import Checkbox from "../Checkbox/Checkbox.svelte";
@@ -237,7 +237,7 @@
   afterUpdate(() => {
     if (checked.length !== prevChecked.length) {
       if (selectionFeedback === "top") {
-        sortedItems = sort();
+        items = sort();
       }
       prevChecked = checked;
       selectedIds = checked.map(({ id }) => id);
@@ -247,33 +247,29 @@
         unselected: unchecked,
       });
     }
+  });
 
-    if (!open) {
-      if (!initialSorted || selectionFeedback !== "fixed") {
-        sortedItems = sort();
+  $: if (!open) {
+    if (!initialSorted || selectionFeedback !== "fixed") {
+      tick().then(() => {
+        items = sort();
         initialSorted = true;
-      }
-
-      highlightedIndex = -1;
-      value = "";
+      });
     }
 
-    items = sortedItems;
-  });
+    highlightedIndex = -1;
+    value = "";
+  }
 
   $: menuId = `menu-${id}`;
   $: inline = type === "inline";
   $: ariaLabel = $$props["aria-label"] || "Choose an item";
-  $: sortedItems = items.map((item) => ({
-    ...item,
-    checked: selectedIds.includes(item.id),
-  }));
-  $: checked = sortedItems.filter(({ checked }) => checked);
-  $: unchecked = sortedItems.filter(({ checked }) => !checked);
-  $: filteredItems = sortedItems.filter((item) => filterItem(item, value));
+  $: checked = items.filter(({ checked }) => checked);
+  $: unchecked = items.filter(({ checked }) => !checked);
+  $: filteredItems = items.filter((item) => filterItem(item, value));
   $: highlightedId =
     highlightedIndex > -1
-      ? (filterable ? filteredItems : sortedItems)[highlightedIndex]?.id ?? null
+      ? (filterable ? filteredItems : items)[highlightedIndex]?.id ?? null
       : null;
 </script>
 
@@ -366,7 +362,7 @@
           change(-1);
         } else if (key === 'Enter') {
           if (highlightedIndex > -1) {
-            sortedItems = sortedItems.map((item, i) => {
+            items = items.map((item, i) => {
               if (i !== highlightedIndex) return item;
               return { ...item, checked: !item.checked };
             });
@@ -394,7 +390,7 @@
           on:clear
           on:clear="{() => {
             selectedIds = [];
-            sortedItems = sortedItems.map((item) => ({
+            items = items.map((item) => ({
               ...item,
               checked: false,
             }));
@@ -424,10 +420,10 @@
           on:keydown|stopPropagation="{({ key }) => {
             if (key === 'Enter') {
               if (highlightedId) {
-                const filteredItemIndex = sortedItems.findIndex(
+                const filteredItemIndex = items.findIndex(
                   (item) => item.id === highlightedId
                 );
-                sortedItems = sortedItems.map((item, i) => {
+                items = items.map((item, i) => {
                   if (i !== filteredItemIndex) return item;
                   return { ...item, checked: !item.checked };
                 });
@@ -489,7 +485,7 @@
         id="{id}"
         aria-multiselectable="true"
       >
-        {#each filterable ? filteredItems : sortedItems as item, i (item.id)}
+        {#each filterable ? filteredItems : items as item, i (item.id)}
           <ListBoxMenuItem
             id="{item.id}"
             role="option"
@@ -503,9 +499,11 @@
                 e.stopPropagation();
                 return;
               }
-              sortedItems = sortedItems.map((_) =>
+
+              items = items.map((_) =>
                 _.id === item.id ? { ..._, checked: !_.checked } : _
               );
+
               fieldRef.focus();
             }}"
             on:mouseenter="{() => {