feat(app): enhance metadata and add admin sidebar section

Update app metadata with multilingual support, SEO improvements, and structured OpenGraph and Twitter metadata. Add an "Administration" section in the sidebar for authenticated admin users. Improve role display and enable dynamic sorting in `HomeContent`. Extend UI badges with a success variant.

frontend/src/components/app-sidebar.tsx

@@ -12,6 +12,7 @@ import {
 	LogOut,
 	PlusCircle,
 	Settings,
+	ShieldCheck,
 	TrendingUp,
 	User as UserIcon,
 } from "lucide-react";
@@ -186,6 +187,26 @@ export function AppSidebar() {
 						</SidebarMenuItem>
 					</SidebarMenu>
 				</SidebarGroup>
+
+				{isAuthenticated && user?.role === "admin" && (
+					<SidebarGroup>
+						<SidebarGroupLabel>Administration</SidebarGroupLabel>
+						<SidebarMenu>
+							<SidebarMenuItem>
+								<SidebarMenuButton
+									asChild
+									isActive={pathname.startsWith("/admin")}
+									tooltip="Dashboard Admin"
+								>
+									<Link href="/admin">
+										<ShieldCheck />
+										<span>Admin</span>
+									</Link>
+								</SidebarMenuButton>
+							</SidebarMenuItem>
+						</SidebarMenu>
+					</SidebarGroup>
+				)}
 			</SidebarContent>
 			<SidebarFooter>
 				<SidebarMenu>
@@ -230,7 +251,7 @@ export function AppSidebar() {
 												<span className="truncate font-semibold">
 													{user.displayName || user.username}
 												</span>
-												<span className="truncate text-xs">{user.email}</span>
+												<span className="truncate text-xs">{user.role}</span>
 											</div>
 										</div>
 									</DropdownMenuLabel>