接单平台新增拼单与取消接单能力

拼单功能：
- 工单/物品规则支持拼单配置（启用、总数量、单价），总价=单价×数量三方联动，启用拼单时工单金额自动同步拼单总价
- 拼单参与按数量冻结比例押金，验收通过后按份额结算报酬，升级统计按数量计入
- 抢单大厅拼单入口：紫色渐变大按钮带单价展示，拼单进度/剩余份数，弹窗输入数量实时预估报酬与押金
- 我的订单展示拼单份额（数量×单价、状态），拼单者各自提交验收，全部提交后管理员统一验收
- 新增 work_order_shares 表与迁移 008

取消接单：
- 进行中订单可取消（押金全额退还、工单回大厅），30 天内限 5 次防滥用

apps/frontend/src/styles/main.css

@@ -1811,13 +1811,43 @@ select {
 }
 
 .worker-hall-card-actions {
-  display: flex;
-  justify-content: space-between;
-  gap: 10px;
-  flex-wrap: wrap;
+  display: grid;
+  gap: 8px;
   margin-top: auto;
 }
 
+.worker-hall-card-actions-row {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 8px;
+}
+
+.worker-hall-card-actions-row .ant-btn {
+  padding-inline: 8px;
+}
+
+.worker-hall-card-grab-row {
+  display: flex;
+  gap: 8px;
+}
+
+.worker-hall-card-grab-row .ant-btn {
+  flex: 1;
+  min-width: 0;
+}
+
+.worker-hall-sharing-button {
+  background: linear-gradient(135deg, #8b5cf6, #7c3aed) !important;
+  border-color: #7c3aed !important;
+  box-shadow: 0 4px 12px rgba(124, 58, 237, 0.28) !important;
+}
+
+.worker-hall-sharing-button:not(:disabled):hover {
+  background: linear-gradient(135deg, #7c3aed, #6d28d9) !important;
+  border-color: #6d28d9 !important;
+}
+
 .worker-hall-detail-stack {
   display: grid;
   gap: 16px;
@@ -1905,11 +1935,15 @@ select {
     padding: 16px;
   }
 
-  .worker-hall-card-actions {
+  .worker-hall-card-actions-row {
     align-items: stretch;
     flex-direction: column;
   }
 
+  .worker-hall-card-grab-row {
+    flex-direction: column;
+  }
+
 }
 
 @media (max-width: 480px) {