fix: an agent's pen keeps the labels the agent already carries

The pen on an agent's page was handed the summary and the path but not the
labels, so the popover offered an empty list over a resource that had some. It
saves every field it shows in one write, and the resource endpoint sets the
column it is given, so adding a label there replaced the agent's own: an agent
labelled `production` and `scheduled` came back from one edit labelled only with
the label just added. A flow's page and a script's page both pass theirs; this
one now does too.

Verified against the running instance: an agent created with
`["production","scheduled"]`, one label added through the pen, reads back
`["production","scheduled","new"]` — and `["new"]` with the prop removed again.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/routes/(root)/(logged)/agents/get/[...path]/+page.svelte

@@ -89,10 +89,14 @@
 </ConfirmationModal>
 
 <main class="h-full w-full flex flex-col">
+	<!-- `labels`: the pen saves every field it shows in one write, so the labels it shows have to be
+	     the ones the resource carries. Handed none, it would offer an empty list, and the first
+	     label added there would replace the agent's own. -->
 	<DetailPageHeader
 		ownsPageHeader
 		itemKind="agent"
 		summary={config ? agent?.state?.description : undefined}
+		labels={agent?.state?.labels}
 		{path}
 		{menuItems}
 		onSaved={canEdit