refactor(dashboard): extract RoleGuard and unify mobile nav with Button

app/(dashboard)/layout.tsx

@@ -1,16 +1,11 @@
 "use client"
 
-import Link from "next/link"
 import { AuthGuard } from "@/components/auth-guard"
 import { DashboardSidebar } from "@/components/dashboard-sidebar"
 import { Header } from "@/components/header"
-import { Button } from "@/components/ui/button"
-import { useAuthStore } from "@/store/auth"
+import { RoleGuard } from "@/components/role-guard"
 
 export default function DashboardLayout({ children }: { children: React.ReactNode }) {
-  const isAuthenticated = useAuthStore((state) => state.isAuthenticated)
-  const currentRole = useAuthStore((state) => state.currentRole)
-
   return (
     <div className="flex min-h-screen flex-col">
       <Header />
@@ -20,15 +15,7 @@ export default function DashboardLayout({ children }: { children: React.ReactNod
         </div>
         <main className="flex-1 p-6">
           <AuthGuard>
-            {isAuthenticated && currentRole === "consumer" ? (
-              <div className="flex min-h-[50vh] items-center justify-center">
-                <Button asChild>
-                  <Link href="/">发现</Link>
-                </Button>
-              </div>
-            ) : (
-              children
-            )}
+            <RoleGuard>{children}</RoleGuard>
           </AuthGuard>
         </main>
       </div>