Use hub exchange instances for calculator contract precision.

Load enabled instances from settings, fetch market info via /api/hub/market, and apply exchange-specific amount and price precision in trend and roll calculators.

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

manual_trading_hub/static/index.html

@@ -707,6 +707,17 @@
           <p class="calc-hint">逻辑与实例策略页一致：首仓 50% + 补仓网格；止损金额 = 资金 × 风险%。</p>
           <form id="calc-trend-form" class="calc-form">
             <div class="calc-form-grid">
+              <label class="calc-field">
+                <span>交易所</span>
+                <select id="calc-trend-exchange" required></select>
+              </label>
+              <label class="calc-field">
+                <span>币种</span>
+                <input id="calc-trend-base" type="text" value="ETH" placeholder="如 ETH" required autocomplete="off" />
+              </label>
+              <div class="calc-field calc-field-span2">
+                <div id="calc-trend-market-info" class="calc-market-info">ETH/USDT · 加载合约信息…</div>
+              </div>
               <label class="calc-field">
                 <span>交易资金 (U)</span>
                 <input id="calc-trend-capital" type="number" min="0.01" step="any" value="1000" required />
@@ -746,10 +757,6 @@
                 <span>补仓档数</span>
                 <input id="calc-trend-dca-legs" type="number" min="1" max="20" step="1" value="5" />
               </label>
-              <label class="calc-field">
-                <span>合约乘数</span>
-                <input id="calc-trend-contract-size" type="number" min="0.0001" step="any" value="1" title="USDT 线性合约默认 1" />
-              </label>
             </div>
             <div class="calc-actions">
               <button type="submit" class="primary">计算</button>
@@ -763,6 +770,17 @@
           <p class="calc-hint">首仓按「单次风险」以损定仓；每次滚仓后合并持仓打到新止损 ≈ 单次风险；止盈锁定首仓价不变。最多 3 次滚仓。</p>
           <form id="calc-roll-form" class="calc-form">
             <div class="calc-form-grid">
+              <label class="calc-field">
+                <span>交易所</span>
+                <select id="calc-roll-exchange" required></select>
+              </label>
+              <label class="calc-field">
+                <span>币种</span>
+                <input id="calc-roll-base" type="text" value="ETH" placeholder="如 ETH" required autocomplete="off" />
+              </label>
+              <div class="calc-field calc-field-span2">
+                <div id="calc-roll-market-info" class="calc-market-info">ETH/USDT · 加载合约信息…</div>
+              </div>
               <label class="calc-field">
                 <span>交易资金 (U)</span>
                 <input id="calc-roll-capital" type="number" min="0.01" step="any" value="1000" required />