fix: context compaction threshold shows while context compaction is off (#32962)

Admins saw the Context Compaction Threshold under Advanced Params, in the model editor, the model defaults and the chat settings, even with context compaction turned off, which is the default, and the value did nothing. It is now hidden while context compaction is off. A threshold already saved on a model is kept and applies again once compaction is turned on.

Refs #32830

src/lib/components/chat/Settings/Advanced/AdvancedParams.svelte

@@ -7,6 +7,7 @@
 	import type { i18n as i18nType } from 'i18next';
 	import { getContext } from 'svelte';
 	import type { Writable } from 'svelte/store';
+	import { config } from '$lib/stores';
 
 	const i18n = getContext<Writable<i18nType>>('i18n');
 
@@ -201,7 +202,9 @@
 				)}
 			{/if}
 		</div>
+	{/if}
 
+	{#if admin && $config?.features?.enable_context_compaction}
 		<div>
 			<Tooltip
 				content={$i18n.t(