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>

crypto_monitor_gate/templates/login.html

@@ -120,14 +120,14 @@
                 <div class="flash">{{ messages[0] }}</div>
             {% endif %}
         {% endwith %}
-        <form method="POST">
+        <form method="POST" autocomplete="off">
             <div class="form-group">
                 <label>账号</label>
-                <input type="text" name="username" required placeholder="请输入账号">
+                <input type="text" name="username" required placeholder="请输入账号" autocomplete="off" autocapitalize="off" spellcheck="false">
             </div>
             <div class="form-group">
                 <label>密码</label>
-                <input type="password" name="password" required placeholder="请输入密码">
+                <input type="password" name="password" required placeholder="请输入密码" autocomplete="new-password">
             </div>
             <button type="submit">登录</button>
         </form>