ui: refine workspace sidebar controls

web/workspace/src/routes/+layout.svelte

@@ -5,15 +5,18 @@
   import type { LayoutProps } from './$types';
 
   let { data, children }: LayoutProps = $props();
+  let sidebarCollapsed = $state(false);
 </script>
 
-<div class="workspace-layout">
+<div class:sidebar-collapsed={sidebarCollapsed} class="workspace-layout">
   <WorkspaceSidebar
     workspace={data.workspace}
     workspaceError={data.workspaceError}
     repositories={data.repositories}
     repositoriesError={data.repositoriesError}
     currentPath={page.url.pathname}
+    collapsed={sidebarCollapsed}
+    onToggleCollapsed={() => (sidebarCollapsed = !sidebarCollapsed)}
   />
   <main class="shell">
     {@render children()}