Add collapsible rule descriptions to trade, strategy, and key pages.

Shared module-rules styling; key monitor rules collapsed by default like other modules.

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

templates/keys.html

@@ -9,9 +9,9 @@
     <div class="card">
         <h2>新增监控</h2>
         <div class="card-body">
-            <details class="key-rules" open>
+            <details class="module-rules">
                 <summary>规则说明</summary>
-                <div class="key-rules-body">
+                <div class="module-rules-body">
                     <p><strong>箱体突破 / 收敛突破（自动单）</strong></p>
                     <ul>
                         <li>触发：<strong>上周期 K 线收盘</strong>收在上沿或下沿之外（默认 5 分）</li>