修复: 审批不超时+重启恢复 + 其他小改

- APPROVAL_TIMEOUT_MS=Infinity(已决策:审批不做超时)
- V33 迁移: ai_conversations 加 pending_approvals 列
- save_conversation 持久化 pending_approvals
- ai_conversation_switch 从 DB 恢复 pending_approvals
- switchConversation 加 try/catch(对话不存在→建新)
- @项目 关联添加取消按钮(×)
- TopBar 底部无标题时图标右对齐
- TaskDetail.vue 删除重复 case

src/views/TaskDetail.vue

@@ -396,8 +396,7 @@ function handleWorkflowEvent(payload: WorkflowEventPayload) {
       break
     }
     case 'workflow_failed':
-    case 'node_failed':
-    case 'workflow_failed': {
+    case 'node_failed': {
       if (evt?.node_id) {
         const node = String(evt.node_id)
         wfNodeStatuses.value = { ...wfNodeStatuses.value, [node]: 'failed' }