(webui) REFACTOR: UI primitives and polish (#19551)

* webui: UI primitives and polish (non-MCP)

* chore: update webui build output

tools/server/webui/src/lib/components/app/misc/ConversationSelection.svelte

@@ -17,9 +17,13 @@
 	let { conversations, messageCountMap = new Map(), mode, onCancel, onConfirm }: Props = $props();
 
 	let searchQuery = $state('');
-	let selectedIds = $state.raw<SvelteSet<string>>(new SvelteSet(conversations.map((c) => c.id)));
+	let selectedIds = $state.raw<SvelteSet<string>>(getInitialSelectedIds());
 	let lastClickedId = $state<string | null>(null);
 
+	function getInitialSelectedIds(): SvelteSet<string> {
+		return new SvelteSet(conversations.map((c) => c.id));
+	}
+
 	let filteredConversations = $derived(
 		conversations.filter((conv) => {
 			const name = conv.name || 'Untitled conversation';
@@ -92,7 +96,7 @@
 	}
 
 	function handleCancel() {
-		selectedIds = new SvelteSet(conversations.map((c) => c.id));
+		selectedIds = getInitialSelectedIds();
 		searchQuery = '';
 		lastClickedId = null;
 
@@ -100,7 +104,7 @@
 	}
 
 	export function reset() {
-		selectedIds = new SvelteSet(conversations.map((c) => c.id));
+		selectedIds = getInitialSelectedIds();
 		searchQuery = '';
 		lastClickedId = null;
 	}