feat(admin): dedicated full-width admin shell in own route group

Admin pages lived under (app)/ and inherited the public 3-column AppShell,
crushing management views into the feed's narrow center column. Move them to
a new (admin) sibling route group with its own AdminShell — a full-width
cockpit with a persistent sidebar nav, slim top bar, and roomy content area.

- New app/(admin)/layout.tsx enforces the ADMIN-role gate once for the whole
  section; per-page gates removed.
- New components/Admin/AdminShell.tsx (sidebar + topbar + fluid content),
  reusing existing design tokens. Content/Insights shown as 'Soon' roadmap.
- URLs unchanged (/admin/*) — route groups don't affect paths.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: NiallJoeMaher

app/(app)/admin/_client.tsx app/(admin)/admin/_client.tsxapp/(app)/admin/_client.tsx renamed to app/(admin)/admin/_client.tsx

@@ -77,7 +77,7 @@ const AdminDashboard = () => {
   const { data: reportCounts } = api.report.getCounts.useQuery();
 
   return (
-    <div className="mx-auto max-w-6xl px-0 py-4 sm:px-4 sm:py-8">
+    <div className="mx-auto max-w-6xl">
       <div className="mb-8">
         <p className="eyebrow">
           <span className="slash">{"// "}</span>admin

app/(app)/admin/moderation/_client.tsx app/(admin)/admin/moderation/_client.tsxapp/(app)/admin/moderation/_client.tsx renamed to app/(admin)/admin/moderation/_client.tsx

@@ -1,5 +1,3 @@
-import { getServerAuthSession } from "@/server/auth";
-import { redirect } from "next/navigation";
 import { Suspense } from "react";
 import ModerationQueue from "./_client";
 
@@ -8,13 +6,8 @@ export const metadata = {
   description: "Review and manage reported content",
 };
 
-export default async function Page() {
-  const session = await getServerAuthSession();
-
-  if (!session?.user || session.user.role !== "ADMIN") {
-    redirect("/");
-  }
-
+// Admin-role gate is enforced in app/(admin)/layout.tsx.
+export default function Page() {
   return (
     <Suspense>
       <ModerationQueue />

app/(app)/admin/moderation/page.tsx app/(admin)/admin/moderation/page.tsxapp/(app)/admin/moderation/page.tsx renamed to app/(admin)/admin/moderation/page.tsx

@@ -0,0 +1,11 @@
+import AdminDashboard from "./_client";
+
+export const metadata = {
+  title: "Admin Dashboard - Codú",
+  description: "Admin dashboard for managing Codú platform",
+};
+
+// Admin-role gate is enforced in app/(admin)/layout.tsx.
+export default function Page() {
+  return <AdminDashboard />;
+}

app/(admin)/admin/page.tsx

@@ -0,0 +1,11 @@
+import Content from "./_client";
+
+export const metadata = {
+  title: "Feed Sources - Admin",
+  description: "Manage RSS feed sources for the content aggregator",
+};
+
+// Admin-role gate is enforced in app/(admin)/layout.tsx.
+export default function Page() {
+  return <Content />;
+}

app/(app)/admin/sources/_client.tsx app/(admin)/admin/sources/_client.tsxapp/(app)/admin/sources/_client.tsx renamed to app/(admin)/admin/sources/_client.tsx

@@ -0,0 +1,11 @@
+import TagsAdmin from "./_client";
+
+export const metadata = {
+  title: "Tag Management - Codú Admin",
+  description: "Manage tags and topics on the Codú platform",
+};
+
+// Admin-role gate is enforced in app/(admin)/layout.tsx.
+export default function Page() {
+  return <TagsAdmin />;
+}

app/(admin)/admin/sources/page.tsx

@@ -0,0 +1,11 @@
+import UserManagement from "./_client";
+
+export const metadata = {
+  title: "User Management - Codú Admin",
+  description: "Search and manage users",
+};
+
+// Admin-role gate is enforced in app/(admin)/layout.tsx.
+export default function Page() {
+  return <UserManagement />;
+}