feat: add impersonate page to handle session token injection and redirection

Coolify injects ARG NODE_ENV=production which causes npm to skip
devDependencies (typescript, tailwindcss, postcss). Override with
ENV NODE_ENV=development before npm install, then set production
before next build.

next.config.mjs

@@ -3,4 +3,5 @@ const nextConfig = {
   transpilePackages: ['@fiberops/shared'],
   output: 'standalone',
 };
+
 export default nextConfig;

src/app/impersonate/page.tsx

@@ -0,0 +1,41 @@
+'use client';
+
+import { useEffect, Suspense } from 'react';
+import { useRouter, useSearchParams } from 'next/navigation';
+
+function ImpersonateHandler() {
+  const router = useRouter();
+  const searchParams = useSearchParams();
+
+  useEffect(() => {
+    const token = searchParams.get('token');
+    const userStr = searchParams.get('user');
+    const tenantStr = searchParams.get('tenant');
+
+    if (token && userStr && tenantStr) {
+      localStorage.setItem('accessToken', token);
+      localStorage.setItem('user', userStr);
+      localStorage.setItem('tenant', tenantStr);
+      localStorage.setItem('is_impersonating', 'true');
+      router.push('/dashboard');
+    } else {
+      router.push('/login');
+    }
+  }, [router, searchParams]);
+
+  return null;
+}
+
+export default function ImpersonatePage() {
+  return (
+    <div className="min-h-screen flex items-center justify-center bg-surface-50 dark:bg-surface-900">
+      <div className="text-center">
+        <div className="w-10 h-10 border-4 border-primary-500 border-t-transparent rounded-full animate-spin mx-auto mb-4"></div>
+        <p className="text-surface-600 dark:text-surface-400">Loading impersonation session...</p>
+      </div>
+      <Suspense fallback={null}>
+        <ImpersonateHandler />
+      </Suspense>
+    </div>
+  );
+}