feat: replace DashboardShell with DashboardPageLayout for improved layout consistency

frontend/src/app/board-groups/new/page.tsx

@@ -6,7 +6,7 @@ import { useState } from "react";
 import Link from "next/link";
 import { useRouter } from "next/navigation";
 
-import { SignedIn, SignedOut, useAuth } from "@/auth/clerk";
+import { useAuth } from "@/auth/clerk";
 
 import { ApiError } from "@/api/mutator";
 import {
@@ -16,9 +16,7 @@ import {
 } from "@/api/generated/boards/boards";
 import { useCreateBoardGroupApiV1BoardGroupsPost } from "@/api/generated/board-groups/board-groups";
 import type { BoardRead } from "@/api/generated/model";
-import { SignedOutPanel } from "@/components/auth/SignedOutPanel";
-import { DashboardSidebar } from "@/components/organisms/DashboardSidebar";
-import { DashboardShell } from "@/components/templates/DashboardShell";
+import { DashboardPageLayout } from "@/components/templates/DashboardPageLayout";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Textarea } from "@/components/ui/textarea";
@@ -125,32 +123,18 @@ export default function NewBoardGroupPage() {
   };
 
   return (
-    <DashboardShell>
-      <SignedOut>
-        <SignedOutPanel
-          message="Sign in to create a board group."
-          forceRedirectUrl="/board-groups/new"
-        />
-      </SignedOut>
-      <SignedIn>
-        <DashboardSidebar />
-        <main className="flex-1 overflow-y-auto bg-slate-50">
-          <div className="border-b border-slate-200 bg-white px-8 py-6">
-            <div>
-              <h1 className="font-heading text-2xl font-semibold text-slate-900 tracking-tight">
-                Create board group
-              </h1>
-              <p className="mt-1 text-sm text-slate-500">
-                Groups help agents discover related work across boards.
-              </p>
-            </div>
-          </div>
-
-          <div className="p-8">
-            <form
-              onSubmit={handleSubmit}
-              className="space-y-6 rounded-xl border border-slate-200 bg-white p-6 shadow-sm"
-            >
+    <DashboardPageLayout
+      signedOut={{
+        message: "Sign in to create a board group.",
+        forceRedirectUrl: "/board-groups/new",
+      }}
+      title="Create board group"
+      description="Groups help agents discover related work across boards."
+    >
+      <form
+        onSubmit={handleSubmit}
+        className="space-y-6 rounded-xl border border-slate-200 bg-white p-6 shadow-sm"
+      >
               <div className="grid gap-6 md:grid-cols-2">
                 <div className="space-y-2">
                   <label className="text-sm font-medium text-slate-900">
@@ -297,10 +281,7 @@ export default function NewBoardGroupPage() {
                 </Link>{" "}
                 and pick this group.
               </div>
-            </form>
-          </div>
-        </main>
-      </SignedIn>
-    </DashboardShell>
+      </form>
+    </DashboardPageLayout>
   );
 }