fix(i18n): stop Farsi links bouncing to /en; locale-aware nav links

- routing: localeDetection:false — a non-prefixed URL always serves fa (default);
  English only via explicit /en/ prefix. Browser Accept-Language no longer
  redirects fa pages to /en on every click.
- AdminShell + DashboardSidebarNav: use next-intl Link + usePathname (from
  @/i18n/navigation) instead of plain next/link, so links preserve the current
  locale and active-state matches the prefix-stripped path.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/admin/AdminShell.tsx

@@ -1,9 +1,9 @@
 "use client";
 
-import Link from "next/link";
-import { usePathname } from "next/navigation";
 import { useState } from "react";
 
+import { Link, usePathname } from "@/i18n/navigation";
+
 export interface NavItem { href: string; label: string }
 export interface NavGroup { title: string; items: NavItem[] }
 
@@ -18,12 +18,10 @@ export function AdminShell({
   back: string;
   children: React.ReactNode;
 }) {
-  const pathname = usePathname() ?? "";
+  const pathname = usePathname() ?? ""; // next-intl: already without the locale prefix
   const [open, setOpen] = useState(false);
 
-  // Strip a leading locale segment (e.g. /en) so fa (no prefix) and en both match.
-  const clean = pathname.replace(/^\/[a-z]{2}(?=\/)/, "");
-  const isActive = (href: string) => clean === href || clean.startsWith(href + "/");
+  const isActive = (href: string) => pathname === href || pathname.startsWith(href + "/");
   const current = groups.flatMap((g) => g.items).find((i) => isActive(i.href));
 
   return (
@@ -68,9 +66,9 @@ export function AdminShell({
           ))}
         </nav>
         <div className="border-t border-[#1e2235] p-3">
-          <a href="/dashboard" className="block rounded-lg px-3 py-1.5 text-sm text-gray-400 hover:bg-[#161a2e] hover:text-white">
+          <Link href="/dashboard" className="block rounded-lg px-3 py-1.5 text-sm text-gray-400 hover:bg-[#161a2e] hover:text-white">
             ← {back}
-          </a>
+          </Link>
         </div>
       </aside>
 
@@ -88,7 +86,7 @@ export function AdminShell({
             <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2"><path d="M3 6h18M3 12h18M3 18h18" /></svg>
           </button>
           <h2 className="text-sm font-semibold text-white">{current?.label ?? brand}</h2>
-          <a href="/dashboard" className="ms-auto text-xs text-gray-500 transition-colors hover:text-gray-300">{back}</a>
+          <Link href="/dashboard" className="ms-auto text-xs text-gray-500 transition-colors hover:text-gray-300">{back}</Link>
         </header>
         <main className="mx-auto max-w-7xl px-5 py-7">{children}</main>
       </div>

src/components/dashboard/DashboardSidebarNav.tsx

@@ -1,8 +1,8 @@
 "use client";
 
-import Link from "next/link";
-import { usePathname } from "next/navigation";
 import { useTranslations } from "next-intl";
+
+import { Link, usePathname } from "@/i18n/navigation";
 import {
   FolderOpen,
   LayoutTemplate,

src/i18n/routing.ts

@@ -7,6 +7,12 @@ export const routing = defineRouting({
   defaultLocale: "fa",
   /** Default locale gets no /fa/ prefix; English is under /en/ */
   localePrefix: "as-needed",
+  /**
+   * Never auto-switch locale from the browser's Accept-Language. A non-prefixed
+   * URL always serves Farsi (the default); English is reached only via an
+   * explicit /en/ prefix — so clicking Farsi links no longer bounces to /en.
+   */
+  localeDetection: false,
 });
 
 export type Locale = (typeof routing.locales)[number];