webui: Add Import/Export of Settings configuration + improve architecture (#22803)

* refactor: Settings keys as constant object keys

* chore: Run `npm audit fix`

* refactor: Settings Sections UI

* feat: Refactor Settings structure and implement import/export logic

* feat: Introduce ROUTES constant and RouterService

* refactor: Consolidate settings definitions into registry

* refactor: Update settings page routing structure

* chore: Migrate hardcoded URLs to use ROUTES and RouterService

* feat: Enhance model selection logic for settings and chat

* chore: Update webui static build

* refactor: Address PR review comments

* fix: Remove unneeded setting

* fix: Re-add missing settings

* fix: Add missing `/slots` proxy for webui dev mode

* chore: Dev-mode logs

* fix: Data binding

* fix: Steering for non-agentic flow

tools/server/webui/src/routes/+error.svelte

@@ -2,6 +2,7 @@
 	import { page } from '$app/stores';
 	import { goto } from '$app/navigation';
 	import { ServerErrorSplash } from '$lib/components/app';
+	import { ROUTES } from '$lib/constants/routes';
 
 	let error = $derived($page.error);
 	let status = $derived($page.status);
@@ -17,7 +18,7 @@
 
 	function handleRetry() {
 		// Navigate back to home page after successful API key validation
-		goto('#/');
+		goto(ROUTES.START);
 	}
 </script>
 
@@ -60,7 +61,7 @@
 				</p>
 			</div>
 			<button
-				onclick={() => goto('#/')}
+				onclick={() => goto(ROUTES.START)}
 				class="rounded-md bg-primary px-4 py-2 text-primary-foreground hover:bg-primary/90"
 			>
 				Go Home