fix: trade_policy 宏使用 with context 修复 500

Jinja imported macros did not receive trade_policy from render context, causing Internal Server Error on all instance pages.

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

lib/strategy/templates/key_monitor_panel.html

@@ -142,7 +142,7 @@
         {% endif %}
     </div>
     <form id="key-form" action="/add_key" method="post" class="form-row">
-        {% from 'trade_policy_fields.html' import trade_policy_symbol, trade_policy_direction %}
+        {% from 'trade_policy_fields.html' import trade_policy_symbol, trade_policy_direction with context %}
         {{ trade_policy_symbol('symbol', 'key-symbol') }}
         <select name="type" id="key-type-select" required>
             {% if position_sizing_mode != 'full_margin' %}