合约管理简化为选品种+填月份，系统自动拼接合约代码

ft-app/app/templates/admin.html

@@ -139,20 +139,16 @@
     <form method="post" action="/admin/contract" style="display:flex;gap:12px;align-items:flex-end;flex-wrap:wrap;">
       <div class="form-group" style="margin-bottom:0;flex:1;min-width:140px;">
         <label>品种</label>
-        <select name="product_id" id="contract-product" required onchange="onProductChange()">
+        <select name="product_id" required>
           <option value="">-- 选择品种 --</option>
           {% for p in products %}
-          <option value="{{ p.id }}" data-code="{{ p.code }}">{{ p.code }} · {{ p.name }}</option>
+          <option value="{{ p.id }}">{{ p.code }} · {{ p.name }}</option>
           {% endfor %}
         </select>
       </div>
       <div class="form-group" style="margin-bottom:0;flex:1;min-width:140px;">
-        <label>合约代码 <span style="font-weight:400;color:var(--sub);font-size:0.75rem;">品种代码加月份</span></label>
-        <input type="text" name="code" id="contract-code" required placeholder="先选品种" maxlength="10" style="text-transform:uppercase;">
-      </div>
-      <div class="form-group" style="margin-bottom:0;flex:1;min-width:100px;">
         <label>月份 <span style="font-weight:400;color:var(--sub);font-size:0.75rem;">如 2609</span></label>
-        <input type="text" name="name" required placeholder="2609" maxlength="4" style="text-transform:uppercase;">
+        <input type="text" name="month" required placeholder="2609" maxlength="4" style="text-transform:uppercase;">
       </div>
       <button type="submit" class="btn btn-primary">添加</button>
     </form>
@@ -216,16 +212,5 @@ function toggleProduct(header) {
   }
 }
 
-function onProductChange() {
-  var sel = document.getElementById('contract-product');
-  var opt = sel.options[sel.selectedIndex];
-  var code = opt.dataset.code || '';
-  var input = document.getElementById('contract-code');
-  if (code) {
-    input.placeholder = code + '2609';
-  } else {
-    input.placeholder = '先选品种';
-  }
-}
 </script>
 {% endblock %}