Migrate more stuff

src/app/components/ChatStart.svelte

@@ -1,4 +1,6 @@
 <script lang="ts">
+  import {preventDefault} from "svelte/legacy"
+
   import {goto} from "$app/navigation"
   import {pubkey} from "@welshman/app"
   import Field from "@lib/components/Field.svelte"
@@ -13,18 +15,24 @@
 
   const onSubmit = () => goto(makeChatPath([...pubkeys, $pubkey!]))
 
-  let pubkeys: string[] = []
+  let pubkeys: string[] = $state([])
 </script>
 
-<form class="column gap-4" on:submit|preventDefault={onSubmit}>
+<form class="column gap-4" onsubmit={preventDefault(onSubmit)}>
   <ModalHeader>
-    <div slot="title">Start a Chat</div>
-    <div slot="info">Create an encrypted chat room for private conversations.</div>
+    {#snippet title()}
+      <div>Start a Chat</div>
+    {/snippet}
+    {#snippet info()}
+      <div>Create an encrypted chat room for private conversations.</div>
+    {/snippet}
   </ModalHeader>
   <Field>
-    <div slot="input">
-      <ProfileMultiSelect autofocus bind:value={pubkeys} />
-    </div>
+    {#snippet input()}
+      <div>
+        <ProfileMultiSelect autofocus bind:value={pubkeys} />
+      </div>
+    {/snippet}
   </Field>
   <ModalFooter>
     <Button class="btn btn-link" on:click={back}>