feat: 报销预审会话状态管理与工作台交互增强

- 新增差旅报销会话状态管理与对话模型重构
- 增强风险观测服务与运行时聊天上下文作用域
- 优化工作台图标资源、助理意图识别与摘要工具
- 完善报销创建视图样式与差旅详情页标准调整交互
- 补充风险观测、运行时聊天与报销端点测试覆盖

web/src/assets/styles/components/travel-reimbursement-message-item.css

@@ -22,6 +22,18 @@
   border-color: rgba(96, 165, 250, 0.3);
 }
 
+.message-stack {
+  min-width: 0;
+  display: grid;
+  justify-items: start;
+  gap: 8px;
+}
+
+.message-row.user .message-stack {
+  order: 1;
+  justify-items: end;
+}
+
 .message-avatar {
   width: 38px;
   height: 38px;
@@ -52,6 +64,94 @@
   box-shadow: 0 10px 22px rgba(148, 163, 184, 0.14);
 }
 
+.steward-intent-bubble {
+  width: min(100%, 680px);
+  border: 1px solid #c9ddea;
+  border-radius: 4px;
+  background: #eef6fb;
+  color: #1f3f5b;
+  box-shadow: 0 8px 18px rgba(148, 163, 184, 0.12);
+}
+
+.steward-intent-bubble[open] {
+  background: #f3f9fd;
+}
+
+.steward-intent-bubble summary {
+  min-height: 38px;
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  padding: 0 12px;
+  cursor: pointer;
+  list-style: none;
+}
+
+.steward-intent-bubble summary::-webkit-details-marker {
+  display: none;
+}
+
+.steward-intent-bubble summary > span {
+  min-width: 0;
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  color: #234a68;
+  font-size: 12px;
+  font-weight: 820;
+}
+
+.steward-intent-bubble summary > span i {
+  color: #3a7ca5;
+  font-size: 14px;
+}
+
+.steward-intent-bubble summary small {
+  margin-left: auto;
+  color: #6f8295;
+  font-size: 12px;
+  font-weight: 720;
+}
+
+.steward-intent-bubble summary > i {
+  color: #64748b;
+  transition: transform 180ms ease;
+}
+
+.steward-intent-bubble[open] summary > i {
+  transform: rotate(180deg);
+}
+
+.steward-intent-event-list {
+  margin: 0;
+  padding: 0 12px 12px 30px;
+  display: grid;
+  gap: 7px;
+}
+
+.steward-intent-event-list li strong {
+  display: block;
+  color: #274b68;
+  font-size: 12px;
+  font-weight: 820;
+}
+
+.steward-intent-event-list li span {
+  display: block;
+  margin-top: 2px;
+  color: #5c7185;
+  font-size: 12px;
+  line-height: 1.55;
+}
+
+.steward-intent-empty {
+  margin: 0;
+  padding: 0 12px 12px;
+  color: #64748b;
+  font-size: 12px;
+  line-height: 1.55;
+}
+
 .message-bubble-application-preview {
   max-width: min(100%, 980px);
 }