fix(auth): stop pre-filling login username on new devices

Remove username_hint from hub auth status API and disable autocomplete on hub and instance login forms.

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

manual_trading_hub/static/login.html

@@ -38,14 +38,14 @@
         <div class="login-sub">CRYPTO MONITOR · COMMAND</div>
       </div>
     </div>
-    <form id="login-form" class="login-form" autocomplete="on">
+    <form id="login-form" class="login-form" autocomplete="off">
       <label class="field">
         <span>用户名</span>
-        <input type="text" name="username" id="login-username" required autocomplete="username" />
+        <input type="text" name="username" id="login-username" required autocomplete="off" autocapitalize="off" spellcheck="false" />
       </label>
       <label class="field">
         <span>密码</span>
-        <input type="password" name="password" id="login-password" required autocomplete="current-password" />
+        <input type="password" name="password" id="login-password" required autocomplete="new-password" />
       </label>
       <button type="submit" class="primary login-submit" id="login-submit">进入系统</button>
       <p id="login-err" class="login-err" hidden></p>
@@ -113,7 +113,6 @@
         .then((r) => r.json())
         .then((s) => {
           if (!s.required || s.logged_in) gotoAfterLogin(null, next);
-          if (s.username_hint && !userInput.value) userInput.value = s.username_hint;
         })
         .catch(() => {});