feat(dashboard): 전역 대시보드 페이지 추가

src/app/(main)/dashboard/page.tsx

@@ -0,0 +1,5 @@
+import DashboardPage from "@/features/dashboard/DashboardPage";
+
+export default function Dashboard() {
+  return <DashboardPage />;
+}

src/app/auth/callback/route.ts

@@ -34,7 +34,7 @@ export async function GET(req: NextRequest) {
       return NextResponse.redirect(new URL("/login?error=auth_failed", req.url));
     }
 
-    return NextResponse.redirect(new URL("/", req.url));
+    return NextResponse.redirect(new URL("/dashboard", req.url));
   } catch (error) {
     console.error("Authentication callback error:", error);
     return NextResponse.redirect(new URL("/login?error=server_error", req.url));

src/components/layout/AppSidebar.tsx

@@ -6,6 +6,16 @@ import { useSession } from "next-auth/react";
 import { useWorkspaceNav } from "@/providers/WorkspaceNavProvider";
 
 const globalNavItems = [
+  {
+    href: "/dashboard",
+    label: "대시보드",
+    icon: (
+      <svg className="w-5 h-5 shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2}
+          d="M3 12l2-2m0 0l7-7 7 7M5 10v10a1 1 0 001 1h3m10-11l2 2m-2-2v10a1 1 0 01-1 1h-3m-6 0a1 1 0 001-1v-4a1 1 0 011-1h2a1 1 0 011 1v4a1 1 0 001 1m-6 0h6" />
+      </svg>
+    ),
+  },
   {
     href: "/",
     label: "프로젝트",
@@ -68,6 +78,7 @@ export default function AppSidebar() {
 
   const isGlobalActive = (href: string) => {
     if (href === "/") return pathname === "/";
+    if (href === "/dashboard") return pathname === "/dashboard";
     return pathname.startsWith(href);
   };