Promote Pro trial and rename settlement source to station

frontend/components/auth/LoginClient.tsx

@@ -71,6 +71,9 @@ export function LoginClient({ nextPath }: LoginClientProps) {
     signupCheckEmail: isEn
       ? "Sign-up successful. Please verify your email before signing in."
       : "注册成功，请检查邮箱并完成验证后登录。",
+    trialPromo: isEn
+      ? "New users unlock a free 3-day Pro trial after sign-up."
+      : "新用户注册后可免费体验 3 天 Pro。",
   } as const;
 
   useEffect(() => {
@@ -190,6 +193,9 @@ export function LoginClient({ nextPath }: LoginClientProps) {
           </div>
           <h1 className="text-3xl font-bold tracking-tight text-white">PolyWeather</h1>
           <p className="mt-2 text-sm text-slate-400">{copy.subtitle}</p>
+          <div className="mt-4 inline-flex items-center rounded-full border border-cyan-400/30 bg-cyan-400/10 px-4 py-1.5 text-xs font-semibold text-cyan-200 shadow-[0_0_20px_rgba(34,211,238,0.08)]">
+            {copy.trialPromo}
+          </div>
         </div>
 
         <button