修复: 全栈审查 FR-C1~C5 五项正确性 bug

- FR-C1 formattedEvents 时间漂移:事件入数组固 _ts 时间戳(project.ts push + ProjectDetail 用 _ts)，computed 重算不再刷历史时间为当前时刻
- FR-C2 sentiment 三档统一:模板 >0/<0/===0 + sentimentClass 同源 + i18n neutral(zh/en)，原模板>0 与 class>=0 矛盾
- FR-C3 Settings timer 泄漏:onUnmounted 清全部三个(原仅 _concurrencyTimer)
- FR-C4 MIGRATION_VERSION 死常量:删(零代码引用,run() if 链自管版本)
- FR-C5 AiConversationDetail 缺 readonly:加 readonly?: boolean(后端 generating 时返回)
来源 fullstack-review §3(已核实);cargo/vue-tsc 0 err

src/stores/project.ts

@@ -11,7 +11,7 @@ const state = reactive({
   tasks: [] as TaskRecord[],
   ideas: [] as IdeaRecord[],
   workflowExecutions: [] as WorkflowRecord[],
-  liveEvents: [] as WorkflowEventPayload[],
+  liveEvents: [] as Array<WorkflowEventPayload & { _ts: number }>,
   pendingApproval: null as {
     execution_id: string
     node_id: string
@@ -209,7 +209,8 @@ function createStore() {
     if (_eventUnlisten) return _eventUnlisten
     _eventUnlisten = await workflowApi.onEvent((payload) => {
       try {
-        state.liveEvents.push(payload)
+        // 固时间戳(FR-C1):formattedEvents computed 重算时用事件发生时刻,非当前时刻
+        state.liveEvents.push({ ...payload, _ts: Date.now() })
         // 处理人工审批请求
         // WorkflowEvent serde tag=type rename_all=snake_case → type='human_approval_request'，字段扁平(无 data 包装)(B-03b-R7)
         if (payload.event?.type === 'human_approval_request') {