第一期骨架：登录、实例登记、多机总览、内嵌/新标签打开。

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

templates/login.html

@@ -0,0 +1,13 @@
+{% extends "base.html" %}
+{% block title %}登录 · 期权中控{% endblock %}
+{% block body %}
+<section class="login-card">
+  <h1>期权中控登录</h1>
+  <p class="muted">关联客户端仓库 crypto_okx · 本仓不下单</p>
+  <form method="post" class="stack">
+    <label>用户名 <input name="username" autocomplete="username" required></label>
+    <label>密码 <input type="password" name="password" autocomplete="current-password" required></label>
+    <button type="submit">登录</button>
+  </form>
+</section>
+{% endblock %}