Rebrand to 比特骆驼自动化对冲系统; clear login autofill and sim subtitle.

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

frontend/src/App.tsx

@@ -14,7 +14,7 @@ function Shell({ children }: { children: ReactNode }) {
     <div className="app-shell">
       <header className="topnav">
         <div className="topnav-side left">
-          <div className="brand">OKX 自动化对冲系统</div>
+          <div className="brand">比特骆驼自动化对冲系统</div>
           <InstallBadge />
         </div>
         <nav className="topnav-center">

frontend/src/pages/Login.tsx

@@ -5,7 +5,7 @@ import InstallBadge from "../components/InstallBadge";
 
 export default function LoginPage() {
   const nav = useNavigate();
-  const [username, setUsername] = useState("admin");
+  const [username, setUsername] = useState("");
   const [password, setPassword] = useState("");
   const [err, setErr] = useState("");
   const [loading, setLoading] = useState(false);
@@ -29,10 +29,9 @@ export default function LoginPage() {
     <div className="login-wrap">
       <form className="login-box" onSubmit={onSubmit}>
         <div className="login-title-row">
-          <h1>OKX 自动化对冲系统</h1>
+          <h1>比特骆驼自动化对冲系统</h1>
           <InstallBadge />
         </div>
-        <p>模拟盘登录 · 支持电脑/平板安装为应用</p>
         {err ? <div className="err">{err}</div> : null}
         <div className="field">
           <label htmlFor="user">用户名</label>

frontend/src/styles/app.css

@@ -144,7 +144,7 @@ input {
 
 @media (max-width: 900px) {
   .topnav-side.left .brand {
-    max-width: 9em;
+    max-width: 11em;
   }
 }
 
@@ -400,7 +400,8 @@ input {
 
 .login-box h1 {
   margin: 0;
-  font-size: 22px;
+  font-size: 20px;
+  line-height: 1.35;
 }
 
 .login-title-row {
@@ -408,7 +409,7 @@ input {
   align-items: flex-start;
   justify-content: space-between;
   gap: 10px;
-  margin-bottom: 6px;
+  margin-bottom: 20px;
 }
 
 .login-box p {
@@ -417,6 +418,10 @@ input {
   font-size: 13px;
 }
 
+.login-box .err {
+  margin-bottom: 14px;
+}
+
 .field {
   display: grid;
   gap: 6px;