refactor(dashboard): reorganize menu actions across sidebar/header/profile

Move shutdown into header popup + profile, move remote into sidebar above
settings, add flag-only language switcher in header, and add language card
plus shutdown/logout actions to the profile page.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/shared/components/Header.js

@@ -6,6 +6,7 @@ import Link from "next/link";
 import PropTypes from "prop-types";
 import ProviderIcon from "@/shared/components/ProviderIcon";
 import HeaderMenu from "@/shared/components/HeaderMenu";
+import HeaderLanguage from "@/shared/components/HeaderLanguage";
 import ThemeToggle from "@/shared/components/ThemeToggle";
 import DonateModal from "@/shared/components/DonateModal";
 import { useHeaderSearchStore } from "@/store/headerSearchStore";
@@ -315,6 +316,7 @@ export default function Header({ onMenuClick, showMenuButton = true }) {
           <span className="hidden sm:inline">Donate</span>
         </button>
         <ThemeToggle />
+        <HeaderLanguage />
         <HeaderMenu onLogout={handleLogout} />
       </div>
       <DonateModal isOpen={donateOpen} onClose={() => setDonateOpen(false)} />