Keep auto-present reminders synchronous to avoid run races

Why: Async notice-run delivery raced with test teardown and in-flight
conversation runs (database closed / material lifecycle flakes).
Evidence: go test ./internal/runmgr/ -run Material
Impact: Reminders append as system messages only; material path still
inlines into startNoticeRun.
Refs: Dev PR #425 CI test-pg failure

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/runmgr/genui_auto.go

@@ -12,8 +12,9 @@ func genUIAutoReminderText() string {
 	return "任务语义事件已发生（阶段或材料/工件完成）。若 generative-ui 已启用，请调用一次 generative-ui.present 生成或修订建议页，按当前任务阶段组织信息。不要点击页面 actions，不要改写 plan/todo/任务完成状态；任务事实只能来自真实任务记录。"
 }
 
-// maybeGenUIAuto：语义事件钩子入口。会话忙碌时只追加 system 消息供下一轮消费；
-// 空闲时启动短 notice-run 让模型有机会立即 present。
+// maybeGenUIAuto：语义事件钩子入口。仅同步追加 system-reminder，供后续回合消费；
+// 不另起 notice-run（避免与在途 run / 测试拆卸竞态）。材料完成路径在
+// startNoticeRun 内联注入同一文案。
 func (m *Manager) maybeGenUIAuto(owner, convID, reason string) {
 	if m == nil || m.genuiAuto == nil {
 		return
@@ -22,34 +23,12 @@ func (m *Manager) maybeGenUIAuto(owner, convID, reason string) {
 	if !ok {
 		return
 	}
-	go m.deliverGenUIAutoReminder(owner, convID, reason)
-}
-
-func (m *Manager) deliverGenUIAutoReminder(owner, convID, reason string) {
 	text := "<system-reminder>\n" + genUIAutoReminderText() + "\n（trigger=" + reason + "）\n</system-reminder>"
 	msg := core.Message{
 		ConversationID: convID, Role: core.RoleSystem,
 		Parts: []core.Part{{Type: core.PartText, Text: text}},
 	}
-	if err := m.st.AppendMessage(&msg); err != nil {
-		return
-	}
-	m.convMu.Lock()
-	busy := m.convActive[convID]
-	m.convMu.Unlock()
-	if busy {
-		return
-	}
-	conv, err := m.st.GetConversation(owner, convID)
-	if err != nil {
-		return
-	}
-	if err := m.claimConversation(convID); err != nil {
-		return
-	}
-	if _, err := m.startClaimedRun(conv, msg, nil, nil, nil); err != nil {
-		m.releaseConversation(convID)
-	}
+	_ = m.st.AppendMessage(&msg)
 }
 
 func planStageChanged(prev, next core.PlanSnapshot) bool {