fix(dashboard): F-U-013 add Refresh + 5s auto-refresh toggle on queues overview

Queue depths change continuously; the page was a load-time snapshot
with no way to update without a hard refresh. Dead-letters has a
Refresh button; queues didn't.

Add:
- A Refresh button that re-fires loadQueues() (and shows "Refreshing…"
  while in-flight).
- An "Auto-refresh every 5s" checkbox. setInterval lifecycle is
  managed via onDestroy so navigating away cancels cleanly.

Queue-detail page is unchanged in this commit; same pattern can be
applied there in a follow-up.

AUDIT.md anchor: F-U-013 (overview list; detail page deferred).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

dashboard/src/routes/apps/[slug]/queues/+page.svelte

@@ -3,11 +3,17 @@
 	import { page } from '$app/state';
 	import { api, ApiError, type App, type QueueSummary } from '$lib/api';
 
+	import { onDestroy } from 'svelte';
+
 	let slug = $derived(page.params.slug ?? '');
 	let app = $state<App | null>(null);
 	let queues = $state<QueueSummary[]>([]);
 	let loading = $state(false);
 	let error = $state<string | null>(null);
+	/// F-U-013: queue depths change continuously. The page used to be a
+	/// page-load snapshot with no way to update without a hard refresh.
+	let autoRefresh = $state(false);
+	let autoRefreshHandle: ReturnType<typeof setInterval> | null = null;
 
 	async function loadApp() {
 		try {
@@ -29,6 +35,23 @@
 		}
 	}
 
+	function setAutoRefresh(on: boolean) {
+		autoRefresh = on;
+		if (autoRefreshHandle) {
+			clearInterval(autoRefreshHandle);
+			autoRefreshHandle = null;
+		}
+		if (on) {
+			autoRefreshHandle = setInterval(() => {
+				void loadQueues();
+			}, 5000);
+		}
+	}
+
+	onDestroy(() => {
+		if (autoRefreshHandle) clearInterval(autoRefreshHandle);
+	});
+
 	$effect(() => {
 		void slug;
 		void loadApp();
@@ -47,6 +70,20 @@
 		Per-app durable queues. Producers call <code>queue::enqueue(name, msg)</code>;
 		consumers register a <code>queue:receive</code> trigger. v1.1.9.
 	</p>
+	<!-- F-U-013: refresh + auto-refresh toggle. -->
+	<div class="toolbar">
+		<button type="button" onclick={() => loadQueues()} disabled={loading}>
+			{loading ? 'Refreshing…' : 'Refresh'}
+		</button>
+		<label class="auto-refresh">
+			<input
+				type="checkbox"
+				checked={autoRefresh}
+				onchange={(e) => setAutoRefresh((e.currentTarget as HTMLInputElement).checked)}
+			/>
+			Auto-refresh every 5s
+		</label>
+	</div>
 </header>
 
 {#if error}