feat(projects-assign): P1+P2+P3 修复 (含服务端超额校验)

P1:
- 截止天数 max=100 + min=1 (前端拦超界输入)
- 合同文件区实装 (support/execute_contract_url 走 Preview.vue, 单条模式显示)

P2:
- 可用金额公式实时显示 (总金额×(1-管理费/总金额)-累计劳务-累计会务)
- 服务端二次校验: BizProjectAssignServiceImpl.validateSum 防前端绕过

P3:
- 命名统一: 支持方→支持单位 / 执行方→执行单位
- 行内删除按钮: 仅剩1 行时禁用第一个
- loading 态: el-descriptions + 批量 info-bar 加 v-loading
- 批量模式加载失败提示: failed 数组 + ElMessageBox.alert

Co-Authored-By: Claude <noreply@anthropic.com>

ry-api/ruoyi-business/src/main/java/com/ruoyi/business/controller/BizProjectController.java

@@ -172,6 +172,7 @@ public class BizProjectController extends BaseController
     public AjaxResult saveAssigns(@PathVariable("projectId") Long projectId, @RequestBody List<BizProjectAssign> assigns)
     {
         if (assigns == null) assigns = new ArrayList<>();
+        bizProjectAssignService.validateSum(projectId, assigns);
         bizProjectAssignService.deleteByProjectId(projectId);
         for (BizProjectAssign a : assigns) {
             a.setProjectId(projectId);

ry-api/ruoyi-business/src/main/java/com/ruoyi/business/service/IBizProjectAssignService.java

@@ -15,4 +15,9 @@ public interface IBizProjectAssignService
     int updateByPrimaryKey(BizProjectAssign entity);
     int deleteByPrimaryKey(String assignId);
     int deleteByProjectId(Long projectId);
+    /**
+     * 校验多个执行方总金额不超过项目总金额 (服务端二次校验, 防前端绕过)
+     * 超额抛 ServiceException
+     */
+    void validateSum(Long projectId, List<BizProjectAssign> assigns);
 }

ry-api/ruoyi-business/src/main/java/com/ruoyi/business/service/impl/BizProjectAssignServiceImpl.java

@@ -1,13 +1,16 @@
 package com.ruoyi.business.service.impl;
 
+import java.math.BigDecimal;
 import java.util.Date;
 import java.util.List;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 import com.ruoyi.business.domain.BizOrg;
+import com.ruoyi.business.domain.BizProject;
 import com.ruoyi.business.domain.BizProjectAssign;
 import com.ruoyi.business.mapper.BizOrgMapper;
 import com.ruoyi.business.mapper.BizProjectAssignMapper;
+import com.ruoyi.business.mapper.BizProjectMapper;
 import com.ruoyi.business.service.IBizProjectAssignService;
 import com.ruoyi.common.exception.ServiceException;
 import com.ruoyi.common.utils.SecurityUtils;
@@ -20,6 +23,8 @@ public class BizProjectAssignServiceImpl implements IBizProjectAssignService
     private BizProjectAssignMapper bizProjectAssignMapper;
     @Autowired
     private BizOrgMapper bizOrgMapper;
+    @Autowired
+    private BizProjectMapper bizProjectMapper;
 
     @Override
     public BizProjectAssign getById(String assignId) { return bizProjectAssignMapper.selectByPrimaryKey(assignId); }
@@ -84,4 +89,27 @@ public class BizProjectAssignServiceImpl implements IBizProjectAssignService
 
     @Override
     public int deleteByProjectId(Long projectId) { return bizProjectAssignMapper.deleteByProjectId(projectId); }
+
+    /**
+     * 校验多个执行方总金额不超过项目总金额 (服务端二次校验, 防前端绕过)
+     * 超额抛 ServiceException, 由 axios 拦截器统一弹 ElMessage.error
+     */
+    @Override
+    public void validateSum(Long projectId, List<BizProjectAssign> assigns) {
+        if (assigns == null || assigns.isEmpty()) return;
+        BigDecimal sum = BigDecimal.ZERO;
+        for (BizProjectAssign a : assigns) {
+            if (a.getAmount() != null) sum = sum.add(a.getAmount());
+        }
+        if (sum.signum() <= 0) return;
+        BizProject p = bizProjectMapper.selectByPrimaryKey(projectId);
+        if (p == null) throw new ServiceException("项目 " + projectId + " 不存在");
+        BigDecimal total = p.getTotalAmount();
+        if (total == null || total.signum() <= 0) return;
+        if (sum.compareTo(total) > 0) {
+            throw new ServiceException(
+                "多个执行方的总金额(" + sum.toPlainString() + ")超过项目总金额(" + total.toPlainString() + ")"
+            );
+        }
+    }
 }