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_focus_v2.html

@@ -34,7 +34,7 @@
     </div>
     <div class="row" style="margin-top:10px">
       <label>币种</label>
-      {% from 'trade_policy_fields.html' import trade_policy_symbol %}
+      {% from 'trade_policy_fields.html' import trade_policy_symbol with context %}
       {{ trade_policy_symbol('symbol', 'symbol-input', default_symbol, placeholder='BTC/USDT') }}
       <label>关键位</label>
       <select id="key-id">

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' %}

lib/strategy/templates/strategy_trend_panel.html

@@ -24,7 +24,7 @@
     {% endfor %}
     {% endif %}
     <form id="trend-pullback-form" action="{{ url_for('preview_trend_pullback') }}" 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', 'trend-symbol', placeholder='BTC 或 ETH/USDT') }}
         {{ trade_policy_direction('direction', 'trend-direction') }}
         <input name="leverage" type="number" min="1" step="1" placeholder="杠杆(必填)" required>

lib/strategy/templates/trade_policy_fields.html

@@ -1,4 +1,7 @@
-{# 方向 / 币种：env 账户级限制（三所共用宏） #}
+{# 方向 / 币种：env 账户级限制（三所共用宏）；调用方须 with context #}
+{% if trade_policy is not defined %}
+{% set trade_policy = {'symbol_restrict_enabled': false, 'direction_restrict_enabled': false, 'symbol_whitelist': [], 'allows_long': true, 'allows_short': true, 'direction_mode': 'both', 'badge_text': ''} %}
+{% endif %}
 {% macro trade_policy_symbol(name, id, value='', required=true, placeholder='BTC 或 BTC/USDT') -%}
 {% if trade_policy.symbol_restrict_enabled and trade_policy.symbol_whitelist %}
 <select name="{{ name }}" id="{{ id }}" {% if required %}required{% endif %} class="trade-policy-symbol-select">