Update environment configuration and enhance Docker setup for production deployment

- Changed NODE_ENV from development to production in .env.example for production readiness.
- Updated WEBUI_URL to point to the new public URL behind Traefik.
- Added internal and external networks in docker-compose.yml for improved service isolation and routing.
- Removed direct port exposure for the WebUI, ensuring it is only accessible through Traefik.
- Refactored landing and login pages in the WebUI to streamline navigation and error handling, redirecting users appropriately based on session status.

apps/webui/src/components/auth/login-card.tsx

@@ -0,0 +1,40 @@
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
+import { getLocale, t } from '@/lib/i18n';
+
+const KNOWN_ERRORS = ['access_denied', 'invalid_request', 'invalid_state', 'oauth_failed'] as const;
+
+export async function LoginCard({ error }: { error?: string }) {
+  const locale = await getLocale();
+  const errorMessage =
+    error && (KNOWN_ERRORS as readonly string[]).includes(error)
+      ? t(locale, `login.errors.${error}`)
+      : undefined;
+
+  return (
+    <main className="flex min-h-screen items-center justify-center px-4">
+      <Card className="w-full max-w-sm">
+        <CardHeader className="items-center text-center">
+          <div className="mb-2 flex size-12 items-center justify-center rounded-xl bg-primary text-lg font-semibold text-primary-foreground">
+            N
+          </div>
+          <CardTitle className="text-xl">{t(locale, 'login.title')}</CardTitle>
+          <CardDescription>{t(locale, 'login.subtitle')}</CardDescription>
+        </CardHeader>
+        <CardContent className="space-y-4">
+          {errorMessage && (
+            <p className="rounded-md border border-destructive/30 bg-destructive/10 px-3 py-2 text-sm text-destructive">
+              {errorMessage}
+            </p>
+          )}
+          <a
+            href="/api/auth/login"
+            className="inline-flex h-10 w-full items-center justify-center gap-2 rounded-md bg-primary text-sm font-medium text-primary-foreground transition-colors hover:bg-primary/90"
+          >
+            {t(locale, 'login.cta')}
+          </a>
+          <p className="text-center text-xs text-muted-foreground">{t(locale, 'login.footer')}</p>
+        </CardContent>
+      </Card>
+    </main>
+  );
+}