✨ feat(contracts): 添加合同已收款金额字段

- 在合同创建表单中新增"已收款金额"输入项
- 支持精确到小数点后两位的金额输入
- 添加最小0、最大999999999999.99的金额限制
- 设置初始值为0以确保数据一致性
- 在合同数据处理中添加receivedAmount字段映射

src/client/admin/pages/Contracts.tsx

@@ -65,6 +65,7 @@ const Contracts: React.FC = () => {
         clientId: record.clientId,
         projectId: record.projectId,
         amount: record.amount,
+        receivedAmount: record.receivedAmount || 0,
         type: record.type,
         status: record.status,
         startDate: record.startDate ? dayjs(record.startDate) : null,
@@ -431,6 +432,23 @@ const Contracts: React.FC = () => {
               />
             </Form.Item>
             
+            <Form.Item
+              name="receivedAmount"
+              label="已收款金额"
+              initialValue={0}
+            >
+              <InputNumber
+                style={{ width: '100%' }}
+                min={0}
+                max={999999999999.99}
+                precision={2}
+                step={0.01}
+                placeholder="请输入已收款金额"
+              />
+            </Form.Item>
+          </div>
+          
+          <div className="grid grid-cols-2 gap-4">
             <Form.Item
               name="currency"
               label="货币类型"
@@ -439,6 +457,8 @@ const Contracts: React.FC = () => {
             >
               <Input placeholder="请输入货币类型" />
             </Form.Item>
+            
+            <div></div>
           </div>
           
           <div className="grid grid-cols-2 gap-4">