feat(web): add dashboard layout with sidebar and header

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/web/components/layouts/dashboard-shell.tsx

@@ -0,0 +1,19 @@
+import { Sidebar } from './sidebar';
+import { Header } from './header';
+
+interface DashboardShellProps {
+  children: React.ReactNode;
+  title: string;
+}
+
+export function DashboardShell({ children, title }: DashboardShellProps) {
+  return (
+    <div className="min-h-screen bg-background">
+      <Sidebar />
+      <div className="pl-64">
+        <Header title={title} />
+        <main className="p-6">{children}</main>
+      </div>
+    </div>
+  );
+}